UNIVERSITY  OF  CALIFORNIA 
AT  LOS  ANGELES 


SOUTHERN  BRANCH, 

UNIVERSITY  OF  CALIFORNIA, 

LIBRARY, 
tjQS  ANGELES,  CALIF. 


PRINCIPLES 

OF 


PLANT    CULTURE 

AN  ELEMENTARY  TRKATISE  DESIGNED  AS 
A  TEXT-BOOK  FOR  BEGINNERS  IN  AG- 
RICULTURE AND   HORTICULTURE 


BY 

E.   S.   GOFF 

PROFESSOR   OF  HORTICULTURE  IN  THE  UNIVERSITY  OF  WISCONSIN 


I &>  Q/7 


THIRD   REVISED  EDITION 


UNIVERSITY   CO-OPERATIVE  CO. 

MADISON,  WISCONSIN 

1906 


14  JlnW  1907 


COPYRIGHT,  1897 
BY     E.    S.    G  O  F  F 


COPYRIGHT  1906 
BY    C.     F.    CRONK 

Administrator  Goff  Estate 


CANTWELL  PRINTING  COMPANY 

MADISON,  WISCONSIN 


PREFACE 

This  book  has  grown  out  of  the  author's  experience 
in  the  lecture  room  and  laboratory,  while  giving  in- 
structions to  students  in  the  Short  Course  in  Agricul- 
ture, in  the  University  of  Wisconsin. 

It  is  intended  especially  for  students  who  have  had 
little  or  no  previous  instruction  in  botany,  and  it  is 
hoped  that  it  may  also  be  found  interesting  and  profit- 
able to  the  general  reader  who  would  learn  more  of  the 
principles  that  underlie  the  culture  of  plants. 

It  is  expected  that  the  instructor  will  amplify  the 
text  in  proportion  to  the  time  at  his  command,  and  the 
capacity  of  his  students.  In  the  author's  practice,  the 
first  three  chapters  have  been  found  sufficient  for  a 
term  of  twelve  weeks,  and  the  remaining  chapters,  sup- 
plemented with  some  special  work  in  horticulture,  have 
served  for  a  second  term. 

A  syllabus  of  laboratory  work  is  added  as  an  ap- 
pendix. 

It  is  hoped  that  this  book  may  prove  as  useful  to 
other  instructors  as  it  has  proved  to  the  author  during 
its  evolution. 

Madison,  Wis.,  Feb.  15,  1897.  E.  S.  GOFF. 


PREFACE  TO  THE  THIRD  EDITION 


Several  changes  have  been  made  in  the  text  of  the 
second  edition.  -  These  changes  were  outlined  by  the 
author  and  preserved  as  marginal  notes  in  a  copy  used 
by  him  in  the  class-room.  In  some  cases  these  notes 
have  been  inserted  without  change,  in  others  where  ab- 
breviated they  have  been  amplified  according  to  what 
is  believed  to  be  the  intent  of  the  author.  This  assump- 
tion is  founded  on  intimate  association  with  the  author 
in  his  work  in  the  preparation  of  the  first  edition  and 
in  later  class  work. 

In  making  changes  an  effort  has  been  made  to  ap- 
proach as  closely  as  possible  to  the  style  of  the  text. 

FREDERIC  CRANEFIELD. 
Madison,  Dec.,  1905. 


ACKNOWLEDGMENTS 


The  author  desires  to  express  his  thanks  to  Prof. 
Charles  R.  Barnes,  of  the  University  of  Chicago,  Prof. 
F.  W.  Woll,  of  the  Wisconsin  Agricultural  Experiment 
Station  and  Mr.  F.  Cranefield,  the  author's  assistant  in 
horticulture,  for  revision  of  the  manuscript  (of  the 
first  edition) ,  and  for  many  valuable  suggestions. 

Figures  14,  15,  18,  19,  20,  21,  22,  28,  29,  30,  34,  46, 
47,  48,  49,  53,  54,  55  and  83  were  copied  from  "Agri- 
cultural Botany, ' '  with  the  sanction  of  the  author,  Prof. 
M.  C.  Potter,  of  the  Durham  College  of  Science,  Eng- 
land. Figures  61,  62,  63,  82,  84,  94,  98,  100,  101,  102, 
103,  113,  117,  118,  119,  120,  121,  123  and  128  are  from 
"The  Nursery  Book,"  by  Prof.  L.  H.  Bailey,  and  are 
used  by  permission.  Figures  31,  59,  81,  85,  99  and  130 
are  from  "The  Amateur  Fruit  Book,"  by  Prof.  S.  B. 
Green,  and  are  used  by  permission.  Figure  32  is  from 
a  photograph  kindly  loaned  by  Prof.  Green.  Figures 
37,  39,  40,  41,  42  and  44  are  copied  by  permission  of 
the  publishers  from  "Barry's  Fruit  Garden."  Fig- 
ures 94  and  95  are  from  "How  to  Make  the  Garden 
Pay, "  by  T.  Greiner,  and  are  used  by  permission.  Fig- 
ures 65  and  66  were  copied  by  permission  from  Bulle- 
tin No.  37,  of  the  Rhode  Island  Agricultural  Experi- 
ment Station.  Figures  77,  78  and  79  are  from  cuts  in 
the  possession  of  the  Wisconsin  Agricultural  Experi- 
ment Station. 


CONTENTS 


PAGE. 

Chapter    I. — Introductory    9 —  21 

Chapter  II.— The  Round   of  Plant  Life 22—118 

Section  1 — The  Behavior  of  Seeds  toward  Water.  22 —  24 

2 — Germination    24 —  32 

3— The    Plantlet    32—  48 

4 — The  Inner  Structure  of  the  Plantlet. .  48 —  56 
"          5 — The    Water   of   Plants   and    its    Move- 
ments       57 —  65 

6— The  Root  and  the  Soil 65—  79 

7— The    Stem    79—82 

8 — The  Leaves  82 —  85 

9— The  Buds  86—  95 

10— The  Flower   95—103 

11— The  Fruit  and  the  Seed 103—106 

12— The  Gathering  and  Storing  of  Seeds..  106—111 
13— The  Decline  of  Growth  and  the  Rest 

Period    111—117 

Chapter  III.— The    Plants   as   Affected   by   Unfavor- 
able Environment    118 — 188 

Section  1 — The  Plant  as  Affected  by  Unfavorable 

Temperature    118 — 136 

A— By   Excessive   Heat 118—121 

B— By  Excessive  Cold 121—127 

Section  2— Methods  of  Averting  Injury  by  Cold..  127—136 

A— During  the  Dormant  Period . . .  127—129 

B — During  the  Growing  Period...  129 — 13G 
Section  3 — The  Plant  as  Affected  by  Unfavorable 

Water   Supply    137—144 

A— By  Excessive  Water 137—141 

B — By    Insufficient    Water 142 — 144 


8  Contents. 

Chapter  III. — Section  4. — The  Plant  as  Affected  by        PAGE 

Unfavorable-^Light    145—149 

A— By    Excessive    Light 145—147 

B— By  Insufficient   Light 147—149 

Section  5 — The  Plant  as  Affected  by  Unfavorable 

Wind     150—151 

A — By    Excessive    Wind 150 

B— By  Insufficient  Wind 151 

Section  6 — The  Plant  as  Affected  by  Unfavorable 

Food    Supply    151—159 

A — By   Excessive   Food 151 — 152 

B — By   Insufficient  Food 152 — 159 

Section  7— The  Plant  as  Affected  by  Parasites ...-.  159— 186 

A— By    Animal    Parasites '. . .   160—178 

B— By  Vegetable   Parasites 178—186 

Section  8— The  Plant  as  Affected  by  Weeds 186—188 

Chapter  IV.— Plant  Manipulation    189—270 

Section  1 — Plant  Propagation   189 — 235 

A— By    Seeds    190—191 

B — By    Division,    i.    e.,    by    parts 

other   than   Seeds 191 — 235 

Section   2 — Transplanting    235 — 252 

A— Lifting   the   Plant 237—239 

B — Removing   the   Plant 239 — 242 

C— Replanting    242—249 

D — After     Care     of     Transplanted 

block    250—252 

Section  3— Pruning    252—269 

A — Formative    Pruning    256 — 262 

B— Stimulative    Pruning    262—266 

C— Protective    Pruning    266 

D — Maturative  Pruning    266 — 267 

Chapter   V. — Plant   Breeding 270 — 280 


PRINCIPLES  OF  PLANT  CULTURE 


CHAPTER  I. 
INTRODUCTORY. 

Before  taking  up  a  systematic  study  of  plant  cul- 
ture, we  may  profitably  consider  a  few  principles  of  a 
more  general  nature. 

1.  Close  Observation  offers  the  best  means  of  gain- 
ing  knowledge   of   material  things.     The  habit  of  ac- 
curate discernment.,   and  of  studying  the  relations  of 
and  the  reasons  for  things  and  facts  as  wre  find  them, 
should     be     constantly     cultivated.      Knowledge     once 
gained  must  be  applied  at  the  proper  place,  the  proper 
manner  and  at  the  proper  time,  or  the  highest  success 
in  any  calling  cannot  be  expected. 

2.  The  Difference  between  Art  and  Science.   Art  is 
simply  knowing  how  to  do  a  thing  without  reference  to 
reasons.     Science  considers  the  reasons  for  doing  it  in  a 
particular  manner.     Art  implies  more  or  less  of  skill 
gained  through  practice.     Science  implies  a  knowledge 
of  the  objects  to  be  gained  by  a  given  operation  and  the 
conditions  affecting  the  process. 

An  intelligent  but  ignorant  person  might  be  taught  to 
prepare  and  insert  a  cion  (386)*  in  the  most  approved 

*  The    numbers    in   parenthesis    in   the   text   refer  to    tha  num- 
bered paragraphs  in  this  book,  and  are  intended  to  help  students 
to    a    better    understanding    of    the    subject.     Students'   should    be 
urged   to    look   up  these   cross    references. 
2 


10  Principles  of  Plant  Culture. 

manner.  This  pertains  to  the  art  of  grafting.  The 
same  person  might  be  taught  the  reasons  why  each  step 
of  the  process  is  performed  in  its  particular  manner. 
This  pertains  to  the  science  of  grafting.  One  may  be- 
come a  skilled  grafter  without  learning  the  science  of 
grafting,  but  he  cannot  graft  intelligently.  The  arti- 
san, however  skillkul,  who  knows  only  the  art,  cannot 
become  a  master  workman  in  the  highest  sense  until  he 
learns  also  the  science  that  underlies  his  trade. 

The  art  of  doing  any  kind  of  work  is  best  learned  by 
working  under  the  guidance  of  a  skilled  workman.  The 
science  is  best  learned  from  books  with  the  help  of 
trained  instructors.  Science  not  yet  wrought  out,  and 
hence  not  explained  in  publications,  is  learned  by  close, 
persistent  and  thoughtful  observation  and  study. 

3.  Environment  is  a  term  used  to  express  all  the  out- 
side influences,  taken  as  a  whole,  that  affect  a  given 
object  in  any  way.     A  plant  or  animal,  for  example,  is 
affected  by  various  external  conditions,  as  heat,  moist- 
ure, light,  food,  etc.  These  conditions  and  all  others  that 
influence  the  plant  or  animal  make  up  its  environment. 

4.  What  is  Culture  '     The  well-being  of  a  plant  or 
animal  depends  very  much  upon  a  favorable  condition 
of  environment,  and  with  the  proper  knowledge,  we  can 
do  much  toward  keeping  the  environment  in  a  favor- 
able  condition.     For  example,  if  the  soil  in  which  a 
plant  is  rooted  lacks  plant  food,  we  can  enrich  it;  if  it 
lacks  sufficient  moisture,  we  can  dampen  it ;  if  the  plant 
is  shaded  by  weeds,  we  can  remove  them.     These,  and 
any  other  things  that  we  can  do  to  make  the  environ- 
ment more  favorable,  constitute  culture  in  the  broadest 


Introductory.  11 

sense  of  the  term.  A  full  knowledge  of  the  culture  of 
any  plant  implies  a  knowledge,  not  only  of  the  plant  and 
its  needs,  but  of  each  separate  factor  in  its  environ- 
ment, and  how  to  maintain  this  factor  in  the  condition 
that  best  favors  the  plant's  development  toward  some 
special  end,  as  the  production  of  the  finest  and  highest 
type  of  fruit,  flowers  or  seed.  We  should  know,  not 
only  the  soil  that  best  suits  the  plant,  but  the  amount  of 
light,  moisture,  warmth  and  food  in  which  it  prospers 
best.  We  should  know  the  enemies  that  prey  upon  it, 
the  manner  in  which  they  work  their  harm,  and  how  to 
prevent  their  ravages.  We  should  know,  in  short,  how 
to  regulate  every  factor  of  environment  so  as  to  pro- 
mote the  plant's  well-being  to  the  utmost,  as  well  as  how 
to  develop  every  desirable  quality  the  p'ant  possesses. 

5.  Domestic   or    Domesticated    Plants    or    Animals 
are  those  that  are  in  the  state  of  culture.     In  nature, 
different  plants  and  animals  struggle  with  one  another 
for  space  and  food.     Only  those  best  adapted  to  their 
environment   survive,    and   these    are   often    much    re- 
stricted in  their  development.     In  culture,  the  intelli- 
gence  and   energy  of  man  produce   a  more   favorable 
environment  for  the  species  he  desires  to  rear;  hence 
domestic  plants  and  animals  attain  higher  development 
in  certain  directions  than  their  wild  parents.     The  cul- 
tivated potato,  for  example,  grows  larger,  is  more  pro- 
ductive and  is  higher  in  food  value  than  the  wild  po- 
tato.    The  finer  breeds  of  horses  and  cattle  are  superior 
to  their  wild  progenitors  in  usefulness  to  man. 

6.  Culture    Aims    to    Improve    Nature's    Methods 
rather  than  to  imitate  them.     By  cutting  out  the  super- 


12  Principles  of  Plant  Culture. 

fluous  branches  from  a  fruit  tree,  we  enable  the  fruit 
on  the  remaining  branches  to  reach  a  higher  state  of  de- 
velopment. By  planting  corn  at  the  proper  distances, 
we  prevent  crowding  and  enable  each  plant  to  attain 
its  maximum  growth.  We  should  constantly  study  na- 
ture's methods  for  useful  hints  in  culture,  and  the  cul- 
ture of  a  given  plant  or  animal  should  be  based  more  or 
less  upon  its  natural  growth  conditions,  but  the  highest 
progress  would  be  impossible  if  we  sought  only  to  imi- 
tate nature. 

7.  Culture  Deals  with  Life.     All  the  products  of  cul- 
ture, whether  obtained  from  the  farm,  garden,  orchard, 
nursery  or   greenhouse,  proceed  directly  or  indirectly 
from  plants  or  animals,  both  of  which  are  living  beings. 
A  knowledge  of  the  conditions  that  sustain  and  promote 
life,  is,  therefore,  the  foundation  to  a  broad  knowledge 
of  husbandry. 

8.  What  is  Life?     We  know  nothing  of  life  except  as 
it  is  manifested  through  the  bodies  of  plants  and  ani- 
mals.    With  these,  we  can  define,  within  certain  limits, 
the  range  of  environment  in  which  it  can  exist;  we  can 
hinder  cr  favor  it ;  we  can  apparently  destroy,  but  we 
cannot  "restore  it.     We  know  that  it  proceeds  from  a 
parental  body  similar  to  its  own,  that  the  body  it  in- 
habits undergoes  a  definite,  progressive  period  of  devel- 
opment, at  the  end  of  which  the  life  disappears  and  the 
body  loses  more  or  less  promptly  its  form  and  properties. 

9.  Vigor  and  Feebleness  are  terms  used  to  express 
the  relative  energy  manifested  by  the  -life  of  different 
living  beings.     Certain  trees  in  the  nursery  row  usually 


Introductory.  13 

outstrip  others  in  growth,  i.  e.,  are  more  vigorous  than 
others.  One  pig  in  a  litter  very  often  grows  slower 
than  any  of  the  others,  i.  e.,  is  more  feeble  or  less  vigor- 
ous than  any  of  the  others.  Feebleness  is  the  opposite 
of  vigor.  The  most  vigorous  plant  or  animal  usually 
attains  the  largest  size,  and  as  a  rule,  is  most  satisfac- 
tory to  its  owner.  Vigor  is  promoted  by  a  favorable 
environment.  It  is  usually  greatest  in  rather  young 
plants  and  animals,  and  declines  with  advancing  age. 
It  may  be  reduced  by  disease  or  improper  treatment, 
and  when  thus  reduced  is  often  difficult  to  restore.  Re- 
duced vigor  tends  to  early  maturity  and  shortened  life, 
and  sometimes  to  increased  prolificacy. 

10.  Hardiness  and  Tenderness  are  terms  used  to  ex- 
press the  relative  power  possessed  by  different  plants  or 
animals  to  endure  extremes  in  their  environment.     The 
Oldenburgh  apple  endures  with  little  harm  vicissitudes 
of  temperature  that  are  fatal  to  many  other  varieties; 
in  other  words,  it  is  hardier  as  regards  temperature 
than  many  other  varieties.   The  reindeer  is  hardier  as  re- 
gards cold  than  the  horse,  but  tenderer  as  regards  heat. 
The  melon  plant  is  hardier  as  regards  heat  and  drought 
than  the  lettuce,  but  tenderer  as  regards  wet  or  cold. 

11.  Health  and  Disease.     A  plant  or  animal  is  said 
to  be  in  health  Avhen  all  its  organs  (parts)  are  capable 
of  performing  their  normal   functions.     An  organ  in- 
capable of  doing  this,  or  the  being  possessing  such  an 
organ,  is  said  to  be  diseased. 

12.  The    Cellular    Structure   of   Living  Beings.     A 
bit  of  vegetable  or  animal  substance,  examined  under  a 


14 


Principles  of  Plant  Culture. 


microscope   of  moderately   high   power,   is   seen   to   be 


B 


made  up  of  numerous  little 
sacks  or  cavities,  more  or  less 
clearly  defined,  called  cells. 
Cells  from  different  beings,  or 
C  from  different  parts  of  the  same 
being,  may  vary  much  in  form 

FIG.  1.     Showing  four  indi-         j       .          ,  -,  •, 

viduai  plants  of  a  species  and  size,  but   they  are  seldom 

of  protococcus.     A   shows  a  . 

plant   before   commencing  to  large    enough    to    be    Seen    Wlth- 
divide     into     other     plants. 

B,  c  and  D  show  how  the  out    magnifying    power.     Some 

cells    divide    to    form    other 

plants.     Highly  magnified.    Of  the   lowest   plants    and   ani- 


FIG.  2.  Part  of  a  filament  of  a  species  of  Spirogyra,  a  plant 
consisting  of  a  single  row  of  cells  united  at  their  ends.  The 
places  where  the  cells  join  are  indicated  by  the  vertical  lines. 
Highly  magnified. 

mals  consist  of  single 
cells  (Fig.  1).  Some  of 
the-  lower  plants  consist 
of  a  single  row  of  cells 
united  at  the  ends  (Fig. 
2 ) .  The  higher  plants  and 
animals  are  made  up  of 
many  cells  united,  and 
in  these,  the  cells  assume 
different  forms  and  prop- 
erties in  the  different  or- 
gans (Fig.  3).  In  some  FIG.  3.  Showing  cells  of  the  ap- 
.,  ,  ,.  Pie  leaf  in  a  section  from  its  up- 

Cases   the  united  Cells    may   per    to    its    lower    surface.      Highly 
magnified.      The    spaces    marked    I 
DC  readily  separated  from  are   cavities    between   the  cells. 

one  another,  which  shows  each  cell  to  be  more  or  less 


Introductory.  15 

an  independent  structure.     As  a  rule,  each  cell  is  sur- 
rounded by  its  own  closed  cell-wall. 

13.  Protoplasm    (pro'-to-plasm).  Living  cells  consist 
of  a  transparent,  jelly-like  substance  called  protoplasm, 
which  manifests  the  various  phenomena  of  life.     Proto- 
plasm may  exist  either  in  an  active  or  dormant  state. 
In  the  active  state  it  requires  both  nourishment  and 
oxygen ;  in  the  dormant  state  it  may  exist  for  a  consid- 
erable time  with  very  little  of  either,  and  is  far  less 
susceptible  to  external  influences  than  in  its  active  state. 
The  protoplasm  contained  in  plants  during  their  rest 
period    (170),    in   mature   air-dry*   seeds,    and  in   the 
lower  animals  during  their  torpid  condition,  is  in  the 
dormant  state. 

14.  Reserve    Food.     Active   protoplasm   may  absorb 
nourishment  in  excess  of  immediate  requirements  and 
hold  it  as  reserve  food.     In  plants,  this  reserve  food  is 
in  the  form  of  starch,  sugar  or  oil ;  in  animals  it  is  in 
the  form  of  fat.     These  substances  are  formed  by  the 
protoplasm   from  its  crude  food  materials    (58).     The. 
reserve  food  enables  the  plant  or  animal  to  live  through 
limited  periods  of  scarcity,  and  to  meet  the  demands 
necessitated  by  reproduction  (16). 

15.  Growth  is  the  normal,  permanent  change  in  the 
form    of   a   living   vegetable   or   animal   body,    and   is 
usually  accompanied  by  increase  in  size.     It  may  occur 
either  through  expansion   of  cells  already  formed,   or 
through  cell  multiplication.     The  latter  may  take  place 
either  by  division  of  older  cells  into  two  or  more  smaller 
cells  (Fig.  1),  or  by  the  formation  of  new  cells  within 

*  Material   is   said  to   be   "air-dry"  when  it   is  as   dry  as   it  will 
become   by   exposure   to   the  air  at   ordinary  temperatures. 


16  Principles  of  Plant  Culture. 

older  ones — the  young  cells  thus  formed  attaining  full 
size  by  subsequent  enlargement. 

16.  Reproduction  is  the  increase  in  number  of  living 
beings.  It  is  one  of  the  properties  of  protoplasm  and 
is  essentially  a  process  of  division.  As  living  cells  mul- 
tiply by  forming  new  cells,  so  living  beings,  which  con- 
sist of  cells,  multiply  by  the  separation  of  a  part  of 
their  own  cells,  and  this  separated  group  of  cells  grows 
into  a  complete  organism  like  the  parent.  The  higher 
plants  multiply  by  seeds  (155),  which  are  separated 
from  the  parent  plant,  and  each  of  which  contains  a 
young  plant  (53).  The  eggs  from  which  young  birds 
are  hatched  contain  cells  filled  with  living  protoplasm, 
and  the  protoplasm  of  the  living  young  of  mammals  is 
separated  from  the  parent  before  birth.  Prolificacy, 
the  faculty  for  reproduction  depends  in  part  upon 
variety. 

16.  Reproduction  is  either  Sexual  or  Non-Sexual. 
Sexual  reproduction  can  take  place,  as  a  ru!e,  only  upon 
"  the  union  of  cells  of  different  sexes.  It  is  not  peculiar 
to  the  animal  kingdom,  but  occurs  in  plants  also,  and 
except  in  rare  cases,  is  necessary  to  the  production  of 
seeds  that  are  capable  of  germination  (28).  It  is  the 
only  method  of  reproduction  in  the  higher  animals. 
Sexual  reproduction  does  not  usually  take  place  until 
the  period  of  most  rapid  growth  has  passed.  Non- 
sexual  reproduction  is  independent  of  sex.  It  results 
from  the  direct  separation  of  a  part  of  the  parent, 
which  under  favorable  conditions  develops  into  a  com- 
plete individual.  It  occurs  when  plants  multiply  by 


Introductory.  17 

means  other  than  by  seeds,  as  by  non-sexual  spores  (52), 
bulbs  (352),  stolons  (348),  cuttings  (358),  etc.,  and  it 
is  a  common  method  of  reproduction  in  certain  of  the 
]ower  animals,  as  plant  lice  (aphidse). 

18.  Heredity    and    Variation.     The  offspring  of   a 
plant  or  animal  tends  to  be  like  the  parent  or  parents. 
But  no  two  beings  can  be  begotten  and  developed  in 
exactly  the  same  environment,  and  since  environment 
always  affects  the  individual  more  or  less,  it  follows 
that  no  two  individuals  can  be  precisely  alike.     Varia- 
tion in  the  offspring  may  take  place  in  any  direction, 
as  in  the  size  or  color  of  the  flower,  the  sweetness  or 
juiciness  of  the  fruit,  the  prolificacy,  the  vigor  (9),  or 
the  hardiness  (10),  etc.     It  follows  that  in  culture  cer- 
tain individual  plants  or  animals  are  more  desirable  to 
the  cultivator  than  others,  because  the  individuals  pos- 
sess different  qualities. 

19.  The  Principle  of  Selection.     Since  the  offspring 
tends  to  resemble  the  parent  or  parents,  we  may  gradu- 
ally  improve    plants    or    animals    in    the   direction    of 
greater  usefulness  by  selecting  the  most  desirable  indi- 
viduals for  reproduction.     For  example,  by  saving  and 
planting  seeds  from  the  plants  that  produce  the  finest 
petunia  or  pansy  blossoms,  we  secure  finer  flowers  than 
if  we  gather  plants  without  regard  to  parentage. 

20.  Breeding  in  plants  and  animals  is  reproduction, 
watched  over  and  directed  by  man,  with  reference  to 
securing  special  qualities  in  the  offspring.     It  is  based 
on  the  principle  that  the  peculiarities  of  the  parent  or 
parents  tend  to  be  reproduced,  and  may  be  intensified, 
in  the  descendants.     But  before  we  are  prepared  for 


18  Principles  of  Plant  Culture. 

the  study  of  breeding,  we  need  to  know  something  of 
the  principles  of  classification. 

21.  Classification  is  the  arrangement  of  the  different 
kinds  of  plants  and  animals  into  groups  and  families 
based  on  individual  resemblances.  If  we  examine  plants 
as  they  are  growing  in  nature,  we  may  observe  (a)  that 
there  are  many  plants  of  the  same  kind,  and  (&)  that 
there  are  many  kinds  of  plants.  The  different  plants 
•  or  animals  of  the  same  kind  are  called  individuals,  and, 
in  general,  we  may  say  that  the  different  kinds  of 
plants  or  animals  are  called  species  (spe'-cies).  But 
these  simple  distinctions  are  not  sufficient  to  satisfy  the 
needs  of  natural  history.  We  might  say,  for  example, 
that  the  violet  is  one  kind  of  plant  and  the  oak  is  an- 
other, which  is  true;  but  there  are  also  different  kinds 
of  violets  and  different  kinds  of  oaks.  We  might  say 
that  the  apple  is  one  kind  of  plant  and  the  pear  is  an- 
other, but  there  are  different  kinds  of  apples,  as  the 
crab  apple  and  the  common  apple,  and  there  are  differ- 
ent kinds  of  crab  apples,  and  of  common  apples.  We 
must  not  only  arrange  the  kinds  of  plants  into  groups, 
but- we  must  have  groups  of  different  grades.  For  ex- 
ample, botanists  call  each  distinct  kind  of  plant,  as 
the  sugar  maple,  the  white  oak  and  the  dandelion,  a 
species.  Then  the  species  that  rather  closely  resemble 
each  other  are  formed  into  groups,  each  of  which  is 
called  a  genus  (ge'-nus),  plural,  genera  (gen'-e-ra)  as 
the  sugar  maple  and  the  soft  maple ;  the  white  oak,  the 
red  oak  and  the  bur  oak;  the  raspberry  and  the  black- 
berry; and  the  apple,  pear  and  quince.  Then  the  gen- 
era that  resemble  each  other,  as  the  one  containing  the 


Introductory.  19 

apple,  pear  and  quince,  and  the  one  containing  the 
plum,  cherry  and  peach,  are  formed  into  other  groups 
called  families.*  Thus  families  are  made  up  of  genera, 
and  genera  are  made  up  of  species.  There  may  be,  also, 
different  varieties  in  the  same  species,  as  the  different 
varieties  of  apple,  pea,  or  strawberry. 

An  extensive  retail  bookstore  furnishes  an  object  les- 
son in  classification,  though  we  must  remember  that  in 
natural  history  it  is  usually  the  names  and  descriptions 
of  plants  and  animals  that  are  classified,  and  not  the 
plants  and  animals  themselves.  In  the  bookstore,  we 
will  observe  that  the  books  are  not  placed  upon  the 
shelves  without  order,  but  that  they  are  arranged  in 
groups.  Different  copies  of  the  same  work  are  placed 
together.  Different  works  on  the  same  subject,  as 
Gray's  botany,  Wood's  botany,  Bessey's  botany  are  also 
placed  in  a  larger  group.  Then  all  the  scientific  books 
are  formed  into  a  still  larger  group,  as  are  the  books  of 
fiction,  the  books  of  poetry,  the  music  books,  etc.  Com- 
paring this  arrangement  with  that  employed  in  natural 
history,  each  separate  work,  as  Gray's  Manual  of  Bot- 
any, Thomas'  Fruit  Culturist,  Bunyan's  Pilgrim's 
Progress,  etc.,  would  correspond  to  a  species,!  and  the 
different  copies  of  the  same  work  would  correspond  to 
individuals.  The  books  treating  of  the  same  general 
subject,  as  the  different  works  on  geology,  botany  or 
arithmetic  would  correspond  to  genera,  and  the  differ- 
ent classes  of  books,  as  scientific  books,  books  of  fiction, 


*  Related    families   are    often   further   united   into    orders. 

t  It  should  not.  however,  be  understood  that  the  different  spe- 
cies of  plants  and  animals  are  always  as  readily  distinguished  as 
are  the  different  works  in  a  bookstore. 


20  Principles  of  Plant  Culture. 

etc.,  would  correspond  to  families.  There  would  also 
be  copies  of  the  same  work  in  different  buildings  which 
would  correspond  to  varieties.  • 

22.  Scientific  Names  are  given  to  plants  and  ani- 
mals because  the  common   names  by  which  they   are 
known  are  so  often  local.     For  example,  quack  grass, 
one  of  our  common  troublesome  weeds,  is  known  by  at 
least   seven   different   common   names  in   this   country 
alone,  and  yet,  in  a  given  locality  it  is  often  known  by 
only  one  name.     Its  scientific  name,  however,  Agropy- 
rum  repens  (a-gro-py'-rum  re'-pens),  is  the  same  in  all 
languages  and  countries.     Scientific  names  are  usually 
Latin  and  consist  of  two  words.     The  first  word  is  the 
name  of  the  genus  to  which  the  plant  or  animal  be- 
longs, and  is  called  the  generic  (ge-ner'-ic)  name;  the 
second  word  designates  the  species,  and  is  called  the 
specific  (spe-cif'-ic)   name.     For  example,  Pyrus  malus 
(py'-rus  ma'-lus)  is  the  scientific  name  of  common  ap- 
ple, Pyrus  being  the  genus  to  which  the  apple  belongs, 
and  malus  designating  which  species  of  the  genus  is 
meant. 

23.  Crosses  and  Hybrids  (hy'-brids).     We  have  seen 
that  in  sexual  reproduction,  a  union  of  male  and  female 
cells  is  almost  always  essential  (17).     When  these  cells 
proceed  from  two  individuals  of  different  varieties  (21, 
436),  the  offspring  is  called  a  cross;  when  they  proceed 
from  individuals  of  different  species,  it  is  called  a  hy- 
brid.   Hybrids  are  possible  only  between  closely-allied 
species   and    are   often   incapable  of   reproduction,   in 
which  case  they  are  said  to  be  sterile.     The  mule,  which 
is  a  hybrid  between  the  horse  and  the  ass,  is  a  familiar 


Introductory.  21 

example  of  a  sterile  hybrid.  Sterile  hybrids  are  not 
uncommon  in  plants.  A  hybrid  that  is  capable  of  re- 
production is  called  a  fertile  hybrid. 

Hybrids  and  crosses  may  resemble  both  parents  about 
equally  or  they  may  resemble  one  parent  more  than  the 
other.  They  sometimes  differ  materially  from  either 
parent.  The  offspring  of  crosses  and  fertile  hybrids  is 
generally  variable  in  proportion  as  their  parents  were 
different  from  each  other,  and  this  variability  may  con- 
tinue through  several  generations. 

24.  The    Theory    of    Evolution,    now   generally    ac- 
cepted by  naturalists,  assumes    that  the  higher  plants 
and  animals  have  been  gradually  evolved  from  lower 
forms,  through  the  principle  that  those  individuals  pos- 
sessing peculiarities  best  fitting  them  to  endure  the  ad- 
verse conditions  of  environment  have  survived  and  per- 
petuated their  kind,  while  others  have  perished. 

25.  Parasites.     Both  plants  and  animals  are  subject 
to  being  preyed  upon  by  other,  usually  smaller,  plants 
and  animals,  that  live  upon  or  within  their  bodies,  con- 
suming the  tissues  of  their  bodies  or  their  reserve  food. 
Plants  or  animals  that  derive  their  nourishment  from 
other  plants   or  animals   are    called  parasites    (par'-a- 
ites)   or  parasitic.     The  plant  or  animal  from  which  a 
parasite  derives  its  nourishment  is  called  a  host.     Para- 
sites are  often  microscopic  in  size.     They  are  generally 
more  or  less  injurious  to  their  host,  and  form  one  of 
the  most  fruitful  sources  of  disease  (270).     Some,  how- 
ever, as  the  micro-organisms  of  the  roots  of  clover  and 
other  leguminous  plants,  are  beneficial  (112). 


CHAPTER   II. 
THE  ROUND  OF  PLANT  LIFE. 

The  earlest  stages  of  plant  growth  occur  in  the  seed, 
hence  this  is  an  appropriate  place  to  commence  our 
study.  We  will  first  consider 

SECTION  1.     THE  BEHAVIOR  OF  SEEDS  TOWARD  WATER. 

26.  Seeds  Absorb  Water  when  placed  in  contact  with 
it.     If  we  fill  a  bottle  with  air-dry  beans,  then  pour  in 
all  the  tepid  water  the  bottle  will  contain,  taking  care 
to  shake  out  the  air  bubbles,  and  place  the  bottle  in  a 
warm  room,  the  beans  will  soon  swell  until  they  have 
pressed  each  other  quite  out  of  shape,  and  no  water 
will  be  forced  out  of  the  bottle.     This  shows  that  the 
beans  have  absorbed  the  water  and  have  swollen  in  con- 
sequence.    This  quality  of  absorbing  water  by  contact, 
at  ordinary  temperatures,  is  possessed  to  a  greater  or 
less  extent  by  most  seeds,  and  indeed  by  nearly  all  air- 
dry  vegetable  material.     It  is  unnecessary  -that  the  seeds 
be  covered  with  water  to  enable  them  to  absorb  it.     If 
in  contact  with  any  moist  medium,  as  a  damp  cloth  or 
damp  earth,  they  will  absorb  moisture  and  swell. 

27.  The    Rate    at  which   Seeds   Absorb   Water   de- 
pends upon  several  Conditions,  as 

a— The  water  content  of  the  medium  with  which  they 
are  in  contact.  If  we  place  one  lot  of  beans  in  water,  a 
second  in  wet  earth  and  a  third  in  slightly  damp  earth, 


The  Behavior  of  Seeds  Toward  Water.  23 

we  shall  find  that  the  first  lot  will  swell  the  fastest,  the 
second  next  and  the  third  slowest.  Few  seeds  will  ab- 
sorb enough  water  from  damp  air  at  ordinary  tempera- 
tures to  swell  much. 

b  —  The  points  of  contact.  If  we^weigh,  two  lots  of 
100  beans  each,  on  a  delicate  balance,  and  mix  each  lot 
with  well-crumbled,  moist  loam  in  a  fruit-jar,  packing 
the  loarn  tightly  in  one  of  the  jars,  and  leaving  it  as 
loose  as  possible  in  the  other,  close  both  jars  to  prevent 
evaporation,  and  after  twenty-four  hours  sift  the  beans 
out  of  the  loam  and  weigh  the  two  lots  again—  we  shall 
find  that  the  beans  in  the  jar  containing  the  compacted 
loam  have  increased  more  in  weight  than  the  others. 
This  indicates  that  the  beans  in  this  jar  have  absorbed 
water  faster  than  those  in  the  other,  because  they  were 
in  contact  with  the  moist  loam  at  more  points. 

c  —  Temperature.  If  we  fill  two  bottles  with  beans, 
adding~ice  water  to  one,  placing  it  in  a  refrigerator,  and 
lukewarm  water  to  the  other,  setting  it  in  a  warm  room, 
we  shall  find  that  the  beans  in  the  latter  bottle  will  swell 
more  rapidly  than  those  in  the  former.  This  shows  that 
a  warm  temperature  favors  the  absorption  of  water  —  a 
fact  that  is  true  of  all  seeds.  The  same  would  have 
been  true  had  we  planted  the  beans  in  two  samples  of 
moist  earth,  placing  these  in  different  temperatures. 
(^  d—The  nature  of  the  seed-case*  In  the  bean,  Indian 


*  The  term  seed-case  is  here  used  to  designate  the  outer  cov- 
ering of  the  seed  as  the  word  seed  is  understood  by  the  seedsman 
or  planter.  Every  seed,  as  we  buy  it  in  the  market,  or  when 
ready  for  planting,  has  one  or  more  covering  layers.  In  the  pea- 
nut, for  example,  what  we  here  call  the  seed-case  is  commonly 
called  the  shuck;  in  the  cocoanut  it  is  called  the  shell;  in  the 
bean  and  Indian  corn  it  is  more  often  called  the  skin.  In  botany, 
the  outer  coverings  of  seeds  are  given  different  names,  as  peri- 
carp, testa,  etc.,  according  to  their  exact  office  in  the  make-up  of 


24  Principles  of  Plant  Culture. 

corn,  wheat  and  many  other  seeds,  the  seed-case  is  of 
such  a  nature  that  it  absorbs  and  transmits  water  read- 
ily. In  certain  seeds,  however,  as  of  the  honey  locust, 
canna,  thorn  apple,  etc.,  especially  if  they  have  been 
allowed  to  become  dry,  the  seed-case  does  not  readily 
transmit  water  at  growing  temperatures.  Such  seeds 
may  lie  for  weeks,  and  even  months,  in  tepid  water 
without  swelling,  but  when  the  water  is  heated  to  a 
certain  degree,  they  swell  promptly,  a  fact  often  turned 
to  account  by  nurserymen  (36).  We  cannot  always 
judge  by  the  appearance  of  a  seed-case  whether  it  will 
transmit  water  readily  or  not. 

SECTION  II.     GERMINATION. 

28.  What  is  Germination?  If  we  place  a  few  viable* 
grains  of  Indian  corn  between  the  moist  cloths  of  a 
seed-tester  (Fig.  6),  cover  with  the  glass  and  place  in  a 
warm  room,  we  shall  observe  if  we  examine  the  corn 
frequently,  that  a  change,  aside  from  the  swelling,  will 
soon  take  place  in  at  least  a  part  of  the  grains.  The 
seed-case  will  be  burst  by  the  pressure  of  a  tiny  white 
shoot  from  beneath.  We  say  that  such  grains  have 
sprouted  or  have  commmenced  to  germinate  (ger'-mi- 
nate),  i.  e.,  have  taken  the  first  visible  step  toward  de- 
veloping into  a  plant. 

We  have  seen  that  the  mature  seed  contains  proto- 
plasm in  its  dormant  condition  (13).  At  a  suitable 
temperature,  the  protoplasm,  on  the  absorption  of 

the  plant.  To  avoid  explaining  the  technicalities  of  a  complex 
subject,  it  seems  preferable  to  adopt  a  term  that  will  include  the 
various  words  used  in  botany  to  designate  the  outer  coverings 
of  seeds. 

*  A  viable  (vi'-a-ble)  seed  is  one  that  is  capable  of  germina- 
tion. Not  all  seeds  are  viable  (164). 


Germination.  25 

water,  resumes  its  active  state,  and  the  cells  of  a  certain 
part  of  the  seeds  begin  to  increase  in  size  and  to  divide1' 
(15),  causing  the  tiny  shoot  to  burst  through  the  seed- 
case.  Germination  is  completed  when  the  young  plant 
(plantlet)  is  sufficiently  developed  to  live  without  fur- 
ther aid  from  the  seed. 

29.  Moisture  is  Essential  to  Germination.     Air-dry 
corn  or  other  seeds  will  not  germinate  if  kept  however 
long  in  a  warm  room,  whereas  viable  seeds,  that  have 
absorbed  water  until  fully  swollen,  will  usually  germi- 
nate if  exposed  to  air  of  a  suitable  temperature,  under 
conditions   that   prevent   their   loss   of  moisture.     This 
shows  that  a  certain  amount  of  moisture  must  be  ab- 
sorbed by  the  seed  before  germination  can  take  place. 
Seeds  must  be  nearly  or  quite  saturated  with  water  be- 
fore they  will  germinate. 

In  culture  we  plant  seeds  in  some  moist  medium; 
usually  the  soil,  in  order  that  they  may  absorb  moisture 
and  germinate,  and  thus  develop  into  new  plants. 

30.  Warmth  is  Essential  to  Germination.     Had  we 
placed  the  seed-tester  mentioned  in  paragraph  28  in  a 
refrigerator  in  which  the  temperature  never  rises  above 
41°  F.,  instead  of  in  a  warm  room,  the  corn   grains 
would  not  have  germinated  however  long  they  remained 
there.     This  shows  that  a  certain  degree  of  warmth  is 
also  necessary  to  germination.     Without  this,  the  pro- 
toplasm of  the  seed  cannot  assume  its  active  state  (13). 
The  lowest  (minimum}  temperature  at  which  seeds  can 
germinate   varies    considerably   with    different    species, 
and  so  does  the  temperature  at  which  they  germinate 
soonest  (optimum}  as  also  the  highest  (maximum}  tern- 


26  Principles  of  Plant  Culture. 

perature  at  which  they  can  germinate.  The  following 
table*  shows  approximately  the  minimum,  optimum  and 
maximum  temperatures  at  which  seeds  of  the  species 
named  germinate. 

MINIMUM.  OPTIMUM.  MAXIMUM. 

Barley 41°  F 77°-88°F 99°-lll°F. 

Bean  (Scarlet  runner) 41  77-88  88-99 

Buckwheat 41  93  115 

Clover  (red) 88-99  99  -111  Ill  -122 

Cucumber 60-65  ..'....88-99  111-122 

Flax 41  77-88  88-99 

Hemp 32-41  99-111  111-122 


Indian  Corn  ....................  41-51 

Lucern  (Alfalfa)  .............  88-99 

Melon  .............................  60-65 

Oat  ................................  32-41 

Pea  .................................  32-41 

Pumpkin  ........................  51-60 

Rye  .................................  32-41 

Sunflower  .......................  41-51 

Wheat  ............................  32-41 


....99  -111  Ill  -122 

....99  -111  Ill  -122 

....88  -99  Ill  -122 

....77  -88  88  -99 

....77  -88  88  -99 

....93  -111  Ill  -122 

....77  -88  88  -99 

....88  -99  99  -111 

....77  -88  ..  88  -108 


These  temperatures  refer  to  the  soil  or  other  medium 
with  which  the  seeds  are  in  contact,  and  not  to  the 
atmosphere. 

When  moisture  is  sufficient,  the  time  from  planting  to 
sprouting  decreases  rapidly  as  we  approach  the  opti- 
mum temperature.  In  an  experiment,  Indian  corn 
sprouted  in  one-third  of  the  time  at  88°  F.  that  it  re- 
quired to  sprout  at  61°. 

Seeds  of  tropical  plants  usually  require  higher  tem- 
peratures for  germination  than  those  of  temperate 
plants. 

t\..*^3i.  Free  Oxygen  is  Essential  to  Germination.     If 
!     we  place  in  the  bottom  of  each  of  two  saucersf  a  layer 

*  Compiled  from   Haberlandt  and   Sachs. 

t  If  flower-pot  saucers  are  used  they  should  first  be  well  soaked 
}n  water,  so  that  they  will  not  extract  water  from  the  soil. 


Germination.  27 

of  puddled*  clay  or  loam,  put  25  viable  beans  on  the 
soil  in  each  saucer,  then  fill  one  saucer  with  moist  sand 
and  the  other  with  puddled  clay  or  loam,  pressing  the 
latter  down  very  closely  around  the  beans,  cover  both 
saucers  with  a  bell-jar,  and  place  in  a  warm  room  for 
two  or  three  days,  we  shall  find  that  the  beans  covered 
with  the  sand  will  sprout  promptly,  while  those  covered 
with  the  puddled  soil  will  not  (Fig.  4).  In  the  sand- 


FIG.  4.  In  the  left  hand  saucer  beans  were  planted  in  puddled 
soil.  In  the  other,  they  were  covered  with  sand.  They  failed  to 
germinate  in  the  puddled  soil,  because  their  contact  with  oxygen 
was  cut  off.  (From  nature.) 

covered  saucer  the  air  between  the  grains  of  sand  has 
had  access  to  the  beans,  while  in  the  other  air  has  been 
shut  out,  which  explains  the  sprouting  of  one  lot  of 
seeds  and  the  failure  of  the  other.  About  one  fifth  of 
the  atmosphere  is  free  oxygen,  i.  e.,  oxygen  that  is  not 
chemically  combined  with  any  other  substance. 

"We  have  seen  that  protoplasm  in  its  active  state  re- 
quires oxygen  (13).  Unless  seeds  are  so  planted  that 
a  certain  amount  of  this  free  oxygen  can  reach  them 
they  cannot  germinate. f  Ordinary  water  contains  a 
little  free  oxygen,  but  not  enough  to  enable  many  kinds 
of  seeds  to  germinate  in  it,  though  the  seeds  of  some 
water  plants,  as  the  water  lily  and  rice,  will  germinate 

*  Soil  is  said  to  be  puddled  when  wet  and  packed  until  it  is 
in  the  consistency  of  putty. 

t  This  probably  explains  why  very  deeply-planted  seeds  rarely 
germinate. 


28  Principles  of  Plant  Culture. 

in  water.  But  even  these  will  not  germinate  in  water 
that  has  been  boiled  long  enough  to  expel  the  oxygen, 
and'is  placed  under  conditions  that  prevent  its  ab- 
sorption again  (Fig.  5). 

We  thus  see  that  seeds  require  three  conditions  be- 
fore  they   can   germinate,    viz.,    a   certain   amount   of 
3,  of  warmth  and  of  oxygen.     In  planting  seeds, 


we  should  consider  all  these  requirements. 

;32.  Prompt  Germination  is  Important.  As  a  rule, 
the  sooner  a  seed  germinates  after  it  is  planted,  the 
better,  for  it  is  generally  in  danger  of  being  destroyed 
by  animals  or  fungi,  and  the  plantlet  probably  loses 

vigor  by  too  slaw 
development. 
Weeds  may  also  be 
gaining  a  start  if 
germination  is  de- 
layed. We  should, 
therefore,  treat 
both  the  seed  and 
the  soil  in  the  way 
that  favors  prompt 
germination. 

FIG.  5.  In  the  left  -bottle,  the  water,  which  had  been  boiled  to 
expel  the  oxygen,  was  covered  with  oil  to  prevent  it  from  absorb- 
ing oxygen  again,  hence  the  rice  seeds  in  it  could  not  germinate. 
In  the  right  bottle  the  water  was  not  covered,  and  so  could  ab- 
sorb oxygen,  permitting  the  seeds  to  germinate.  (From  nature.) 


33.  Compacting  the  Soil  about  planted 
Hastens  Germination  by  multiplying  their  points  of 
contact  with  the  moist  earth  (276).  When  the  soil  is 
becoming  drier  day  by  day,  as  it  often  is  in  spring, 
compacting  the  soil  about  planted  seeds  materially 


Germination.  29 

hastens  their  germination  and  often  secures  germina- 
tion that  without  the  compacting  might  be  indefinitely 
postponed.  The  hoe,  the  feet,  a  board  or  the  hand-  or 
horse  roller  may  be  used  to  compact  soil  over  planted 
seeds.  Seeds  planted  in  flower  pots  or  in  boxes  or 
beds  in  the  greenhouse  or  hot-bed,  however,  should  not 
have  the  soil  unduly  packed. 

34.  Planting  should  be  Deferred  until  the  Soil  be- 
comes Warm.     Seeds  cannot  germinate  promptly  until 
the  temperature  of  the  soil  in  which  they  are  planted 
approaches   the   optimum   for   their  germination    (30) 
during  the  warmer  part  of  the  day,  and  germination  is 
promoted  little,  if  at  all,  by  planting  before  this  time. 

35.  Germination    may    be    Hastened    by    Soaking 
seeds   before   planting.     Since   seeds   cannot  germinate 
until  nearly  or  quite  saturated  with  water   (29),  and 
since  they  absorb  water  faster  from  ti  very  wet  than 
from  a  damp  medium  (270),  and  in  a  warm  than  in  a 
cool  temperature  (27c),  we  may  hasten  germination  a 
little  if  the  soil  to   receive  the   seeds  is  only  slightly 
moist,  by  soaking  the  seeds  before  planting  in  warm  or 
slightly  hot  water  until  they  have  swollen.  This  method 
is   sometimes  practiced  by  gardeners  with  sweet  corn 
and  certain  other  seeds,  and  its  use  might  possibly  be 
extended  with  profit.     The  water  should  be  heated  only 
to  110°  or  120°  F.  and  the  soaking  may  be  continued 
until  the  seeds  have  fully  swollen. 

Soaking  is  most  important  with  seeds  having  seed- 
cases  that  do  not  readily  transmit  water  at  growing  tem- 
peratures, as  in  the  honey  locust,  canna,  thorn  apple, 
hawthorn,  holly,  peony,  etc.  (27d).  Such  seeds,  par- 


30  Principles  of  Plant  Culture. 

ticu^arly  if  they  have  been  allowed  to  become  dry,  are 
generally  soaked  in  hot  water  until  swollen,  before 
planting,  otherwise  they  might  lie  in  the  ground  for 
months  and  even  years  before  germinating.  In  treat- 
ing such  seeds  with  hot  water,  unless  the  temperature 
at  which  they  swell  is  known,  the  water  should  be 
heated  very  gradually  until  the  seeds  begin  to  swell, 
when  it  should  be  maintained  at  that  temperature  until 
they  are  fully  swollen.  It  is  said  that  seeds  of  the  honey 
locust  may  be  immersed  for  a  time  in  boiling  water  with- 
out destroying  their  vitality,  but  such  treatment  is  not 
to  be  recommended  for  any  seeds.  In  seeds  of  this  class, 

36.  Germination  is  sometimes  Hastened  by  Cracking 
or  Cutting   Away  part  of  the  Seed-Case.     To   favor 
the  absorption  of  water,  nurserymen  often  drill  or  file 
a  hole  through  the  bony  seed-cases  of  nelumbium  seeds, 
or  crack  dry  peach  and  plum  pits  in  a  vise  or  with  an 
implement  resembling  a  nutcracker  (27 d). 

37.  Seeds  may  Fail  to  Germinate  from  a  variety  of 
causes,   even   when   exposed  to   the   proper   degree   of 
warmth,  moisture  and  oxygen.  I  They  may  be  too  old 
(164)^they  may  not  have  been  sufficiently  mature  when 
gathered  (162)pthey  may  have  become  too  dry  (168), 

N&they  may  have  been  subjected  to  freezing  before  suffi- 
ciently dry  (166$,  they  may  have  been  stored  while 
damp  and  thus  subjected  to  undue  heating,  \>r  they 
may  have  been  damaged  by  insects  or  fungi  (321) 
either  before  or  after  maturity.  Defects  of  these  kinds 
are  not  always  visible,  hence 

38.  Seeds  should  be  Tested  before  Planting  to  learn 
if   they  will    germinate.     It    is    unnecessary    to    plant 


Germination.  31 

seeds  in  soil  to  test  them,  since  the  seed-tester  shown  in 
Fig.  6  is  much  more  convenient.  This  useful  device  con- 
sists of  two  circular  pieces  of  clean,  moderately  thick 
cloth  of  rather  loose  texture,  a  table  plate  that  is  not 
warped,  and  a  pane  of  glass  large  enough  to  cover  the 
plate.  The  cloths  are  dipped  in  water,  and  squeezed  a 
few  times  while  under  the  water  to  press  out  the  air. 


FIG.   6.     Showing-  a  simple  seed-tester,  adapted  to  farmers'  and 
gardeners'   use. 

They  are  then  wrung  out  until  moderately  wet,  and 
spread  over  the  bottom  of  the  plate  as  shown,  and  the 
seeds  to  be  tested  are  placed  between  them.  It  is  well 
to  use  a  hundred  or  more  seeds  of  each  sample,  as  a 
larger  number  will  show  the  per  cent  of  vitality  more 
accurately  than  a  smaller  one,  and  the  lot  should  al- 
ways be  well  mixed  before  taking  the  sample.  The 
plate  should  be  kept  covered  with  the  glass  to  prevent 
evaporation  from  the  cloths,  and  it  may  be  placed  in 
any  room  of  comfortable  living  temperature.  The  seeds 
should  be  frequently  examined,  and  may  be  removed  as 
they  sprout,  when  by  subtracting  the  number  that  fail 
to  sprout  from  the  number  put  in,  the  per  cent  of  vi- 
tality may  be  readily  computed.  The  cloths  should  be 


32  Principles  of  Plant  Culture. 

placed  in  boiling  water  a  few  minutes  before  using  them 
for  a  second  test,  to  destroy  any  spores  or  mycelia  of 
mold  with  which  they  may  have  become  infected. 

39.  The    Time    Required    for    Germination    varies 
greatly  in  different  kinds  of  seeds.    'In  lettuce  seed,  the 
tiny   white   shoot   often   breaks   through   the   seed-case 
within  twenty-four  hours  from  planting,  while  celery 
seed  requires  several  days  to  germinate  to  this  extent. 
The  seeds  of  many  plants  will  not  germinate  the  same 
season  they  are  formed,  even  if  planted  under  the  most 
favorable  conditions   (162). 

Individual  seeds  of  the  same  kind  and  of  the  same 
sample  often  vary  greatly  in  the  time  required  for  ger- 
mination. Even  in  seeds  that  germinate  soonest,  as 
lettuce  and  radish,  some  individuals  will  not  germinate 
until  several  days  after  the  majority  have  germinated. 
Seeds  of  tobacco  and  purslane*  sometimes  continue  to 
germinate  through  several  successive  seasons.  The  rea- 
sons for  these  variations  are  not  known. 

SECTION  III.     THE  PLANTLET. 

By  watching  the  germination  of  seeds,  we  may  learn 
some  interesting  facts.  Viable  seeds  will  usually  germi- 
nate freely  on  the  surface  of  well-moistened  soil  or  sand, 
if  we  provide  a  damp  atmosphere  above  them  by  cover- 
ing with  a  bell- jar  or  otherwise,  for  light  does  not  hin- 
der germination.  One  of  the  interesting  facts  connected 
with  germination  is,  that  the  first  shoot,  called 

40.  The   Hypocotyl*    (hy'-po-co'-tyl)    Grows   Down- 
ward, on  emerging  from  the  seed-case  (27d),  no  matter 

*Pottulaca  oleracea. 


The  Plantlet.  33 

in  what  position  the  seed  is  placed.  It  will  curve  in  a 
semi-circle  if  necessary,  to  bring  its  rounded  point  in 
contact  with  the  soil.  But  the  hypocotyl  is  not  always 
able  to  enter  the  soil,  unless  the  seed  is  covered  more 
or  less,  because  the  resistance  offered  by  the  soil  is  often 
greater  than  the  weight  of  the  seed.  On  this  account, 
as  well  as  to  insure  a  supply  of  moisture,  it  is  best  to 
cover  most  seeds  at  planting,  or  at  least  to  press  them 
well  into  the  soil  (51).  In  nature,  seeds  usually  be- 
come more  or  less  covered,  and  these  not  covered  gen- 
erally fail  to  germinate. 

41.  The  Seed-Case  in  Germination.  After  germina- 
tion commences,  the  seed-case  is  of  no  further  use.  It 
has  fulfilled  its  purpose,  which  is  to  protect  the  seed 
from  the  time  of  its  maturity  until  the  conditions  ar- 
rive for  germination,  and  is  henceforth  a  hindrance  to 
germination  in  many  plants,  as  it  must  be  torn  asunder 
by  the  expanding  plantlet.  If  we  watch  the  germina- 
tion of  squash  or  pumpkin  seeds  through  the  different 
stages,  we  may  discover  that  nature  has  made  a  special 
provision  to  help  the  plantlet  in  escaping  from  the  seed- 
case  in  these  plants.  As  the  hypocotyl  curves  down- 
ward, a  projection  or  hook  is  formed  en  the  side  toward 
the  seed,  which  holds  the  seed-case  down  while  the  seed- 
leaves  are  pulled  out  from  it.  The  action  of  this  hook 
is  shown  in  the  accompanying  figures.  Sometimes,  as 
shown  in  C,  the  point  of  the  seed-case  breaks,  permit- 
ting the  hook  to  slip  off,  and  if  the  seed  happens  to  be 
planted  edgewise  or  with  the  point  downward,  the  hook 
often  fails  to  catch  the  seed-case,  as  in  D,  and  so  the 


Often    called    radicle   and   caulicle. 


34 


Principles  of  Plant  Culture. 


plantlet  emerges  from  the  soil  without  freeing  itself 
from  the  seed-case  and  is  hampered  for  a  time.  This 
provision  is  peculiar  to  the  pumpkin  family,*  to  which 
the  pumpkin,  squash,  cucumber  and  melon  belong, 
though  other  provisions  which  accomplish  the  same  end 


FIG.  7.  Showing  nature's  provision  to  enable  the  pumpkin 
plantlet  to  escape  from  the  seed-case.  In  A,  the  hook  on  the 
hypocotyl  is  attached  to  the  lower  half  of  the  seed-case.  B  shows 
the  same  after  germination  is  farther  advanced.  A  fully-germi- 
nated pumpkin  plantlet  is  shown  at  Fig.  8. 

are  found  in  a  few  other  families,  but  many  plants  aTe 
considerably  held  back  by  the  seed-case  during  ger- 
mination. 

42.  Seeds  of  the  Pumpkin  Family  should  be  Planted 
Flatwise,  rather  than  edgewise  or  endwise,  since  in  this 
position  they  most  readily  free  themselves  from  the 


43.  Some  Plantlets  Need  Help  to  Burst  the  Seed- 
Case.  In  many  seeds  having  hard  and  strong  seed- 
cases,  as  the  walnut,  butternut  and  hickory  nut  and  the 


*  Natural   order  Cucurbitaceae. 


The  Plantlet. 


35 


pits  of  the  plum,  peach  and  cherry,  the  enlarging  plant- 
let  is  often  unable  to  burst  the  seed-case,  hence  germi- 
nation cannot  take  place  unless  assisted  by  the  expand- 
ing power  of  frost,  or  long  exposure  to  moisture  which 
softens  the  seed-case,  or  unless  the  seed-case  is  cracked 
before  the  seeds  are  planted  (36). 

44.  The  Roots  promptly  start,  as  the  hypocotyl 
emerges  from  the  seed-case — the  main  (primary)  root 
from  its  point,  and  the  branch  (lateral)  roots  from  its 


FIG.  8.  Plantlet     FIG.  9.  Plantlet     FIG.  10.  Plantlet     FIG.  11.  Plantlet 
of  pumpkin.  of  bean.  of  Indian  corn.  of  pea. 

In    the    pumpkin    and    bean,    the    seed-leaves    (cotyledons)    are 

lifted  above  the  surface   cf   the  soil  in   germination. 

In  the  pea,   the  cotyledons  are    not    lifted  above  the  surface  of 

the  soil  in  germination. 

side.  Sometimes  root-hairs  (100)  may  be  distinctly 
seen,  especially  when  seeds  germinate  in  the  seed-tester 
(38). 

By  studying  Figs.  8  to  11,  we  may  learn  more  of  the 
germinating  process. 

45.  The  Cotyledons  (co-ty-le'-dons).  In  the  bean 
and  pumpkin,  the  seed,  or  what  remains  of  it,  seems  to 


36  Principles  of  Plant  Culture. 

have  separated  into  two  parts  that  are  united  at  one 
end — the  cotyledons  or  seed-leaves.  In  the  bean  and 
pumpkin,  the  cotyledons  form  a  pair  of  clumsy  leaves, 
which  in  the  bean  point  downward  at  first,  but  after- 
wards become  upright,  by  the  straightening  of  hypo- 
cotyl  beneath  them.  We  observe  that  the  pea  has  also 
a  pair  of  cotyledons  (c),  which  have  not  separated  to 
the  same  extent  as  those  of  the  bean  and  pumpkin  and 
are  still  beneath  the  soil.  The  corn,  in  common  with 
other  plants  of  its  class,  as  sorghum,  sugar  cane,  the 
reeds,  grasses,  etc.,  has  but  one  cotyledon,  and  that  is 
not  easily  seen  without  dissecting  the  seed.  In  Fig.  14, 
which  shows  a  cross-section  of  the  germinating  corn 
grain,  the  cotyledon  appears  at  cot. 

The  plants  having  two  cotyledons  form  a  very  im- 
portant class  in  botany,  known  as  Dicotyledones  (di-co- 
tyl-e'-dones)  ;  those  having  but  one  cotyledon  form  a 
class  known  as  Monocotyledones  (mo'-no-co-tyl-e'- 
dones).  There  is  also  a  class,  including  the  pine,  fir 
and  other  conifers,  that  have  several  cotyledons. 

46.  The  Hypocotyl   Develops  Differently  in  Differ 
ent   Species.     In  the  pea    (Fig.   11)    and  some   other 
plants,  the  cotyledons  remain  in  the  soil,  while  in  the 
bean  and  pumpkin,  they  have  been  lifted  bodily  into 
the  air.     This  striking  difference  is  due  to  the  fact  that 
in  the  pea,  the  hypocotyl  lengthens  very  little  in  ger^ 
mination,  while  in  the  bean  and  pumpkin,  it  lengthens 
comparatively  very  much. 

47.  Seeds    in    which   the    Hypocotyl    Lengthens    in 
germination    Must    Not   be    Deeply    Planted.      When 
seeds  of  this  class,  which  includes  many  plants  beside 


The  Plantlet. 


.'57 


the  bean  and  pumpkin,  are  planted  in  soil,  the  cotyle- 
dons must  be  forced  through  the  soil  above  them,  an 
act  requiring  considerable  en- 
ergy. If  such  seeds  are  covered 
with  much  soil,  the  plantlet  is 
often  unable  to  lift  its  cotyle- 
dons to  the  surface,  and  hence 
must  perish.  Fig.  12  shows  two 
bean  plantlets  that  tore  off  their 
cotyledons  in  the  vain  attempt 
to  lift  them  through  five  inches 
of  soil.  The  plantlet  of  wheat, 
barley  and  oats,  though  much 
smaller  and  weaker  than  that  of 
the  bean,  readily  grows  through 

FlJl2.  Showing  two  bean  this  dePth  °f  Soil>  beC&USe  the 
plantlets  that  tore  off  their  finv  -nmntpr^  shoot  (nlnrnnlp 
cotyledons  from  being  too  CmV  P01 

(55) )  of  these  plants  readily  in- 
sinuates itself  between  the  soil  particles  and  comes  to 
the  surface  with  little  expenditure  of  energy,  even  when 
deeply  planted.  Plantlets  of  the  larger  beans  usually 
fail  if  the  seeds  are  planted  three  inches  deep  in  a 
clay  soil  that  bakes  above  them.  Those  of  the  castor 
bean,*  though  very  robust,  can  hardly  lift  their  cotyle- 
dons through  one  inch  of  soil,  while  those  of  the  pea, 
though  much  more  slender,  readily  grow  through  four 
to  six  inches.  Apple  seeds  planted  in  autumn  on  clay 
soil,  usually  fail  to  germinate  the  following  spring 
unless  covered  with  sand  or  humus,  or  carefully 
mulched,  because  the  plantlets  are  unable  to  lift  their 
cotyledons  through  a  baked  surface  soil. 

*  Ricinus. 


38 


Principles  of  Plant  Culture. 


48.  The  Vigor  of  the  Plantlet  is  generally  in  Pro- 
portion to  the  Size  of  the  Seed.     This  is  true  not  only 
between  different  kinds  of  seeds,  but  between  different 

seeds  of  the 
same  kind.  The 
larger  beans, 
the  horse  chest- 
nut and  the 
walnut  form 
much  stronger 
plantlets  than 
clover,  timothy 
and  tobacco, 

FIG.  13.     Showing  navy  bean  plants  grown  from   and    the  largest 
large  seeds   (left)   and  from   small  seeds  (right). 

and    plumpest 

specimens  of  any  sample  of  seed  usually  form  stronger 
plantlets  than  the  smaller  and  more  shrunken  specimens. 
Growers  of  lettuce  under  glass  are  sometimes  able  to 
raise  one  more  crop  during  the  winter  by  sowing 
only  the  largest  seeds  than  when  the  seed  is  sown  with- 
out sifting.  The  practice  of  sifting  seeds  before  plant- 
ing, and  rejecting  the  smaller  ones,  should  be  more 
generally  followed  (Fig.  13). 

49.  The  Earlier  Germinations  from  a  sample  of  seed 
often  Form  More  Vigorous  Seedlings  than  the  Later 
Ones.     This  is  one  of  nature's  method  for  preserving 
the  vigor  of  plants.     The  stronger  seedlings  overtop  the 
later  and  feebler  ones  and  crowd  them  out  of  exist- 
ence.    We  should  profit  by  this  hint  and  reject  the  later 
plants  in  the  seed-bed. 

50.  How  Deep  should  Seeds  be  Planted?     We  have 
seen  that  one  object  of  planting  seeds  in  the  soil  is  to 


The  Plantlet.  39 

place  them  in  contact  with  moisture  (29).  Since  the 
plantlet  must  force  its  way  through  the  soil  that  covers 
the  seed,  the  less  the  depth  of  this  soil,  other  things 
equal,  the  less  energy  and  the  shorter  time  are  required 
for  the  plantlet  to  reach  the  surface.  Therefore,  seeds 
should  not  be  planted  deeper  than  is  necessary  to  insure 
the  proper  supply  of  moisture. 

Small  seeds,  as  of  lettuce,  celery  and  carrot,  produce 
such  weak  plantlets  that  it  is  unsafe  to  cover  them  suf- 
ficiently to  insure  the  proper  moisture  supply  in  dry 
weather.  We  must,  therefore,  plant  such  seeds  so 
early  in  spring  that  the  soil  has  not  had  time  to  become 
dry,  or  if  necessarily  planted  later,  we  must  depend 
largely  upon  artificial  watering. 

51.  Very   Small   Seeds,   as   of  petunia  and  tobacco, 
Should  Not  Be  Covered  with  soil  at  all,  but  may  be 
pressed  down  into  fine  loam  with  a  board  or  otherwise, 
and  must  be  watered  often  with  a  fine-rose  watering-pot. 
When  small  seeds  are  sown  in  full  exposure  to  sunlight, 
it  is  well  to  shade  the  surface  with  paper  or  a  muslin- 
covered  frame,  to  check  evaporation  until  the  plantlets 
appear.    Small  seeds  are  sometimes  covered  with  a  thin 
layer  of  spagnum  moss  that  has  been  rubbed  through  a 
sieve.     This  helps  to  retain  moisture  in  the  surface  soil. 

52.  Ferns  are  Grown  from  Spores*  sown  on  the  sur- 
face of  fine  soil  in  a  propagating  frame  (369),  in  which 

*  Spores  are  the  chief  reproductive  bodies  in  plants  that  pro- 
duce no  seeds,  as  ferns,  mushrooms,  mosses,  etc.  They  are  usually 
so  small  as  to  be  barely  visible  to  the  unaided  eye.  The  dust 
that  escapes  from  a  puff  ball  when  it  is  squeezed  or  from  a 
bunch  of  corn  smut  is  formed  of  the  spores  of  these  plants. 
Spores  usually  consist  of  a  single  cell,  in  which  respect  they 
differ  materially  from  seeds,  which  contain  a  more  or  less  devel- 
oped plantlet  (53). 


40  Principles  of  Plant  Culture. 

the  air  is  kept  very  moist  and  the  surface  of  the  soil 
never  becomes  dry. 

53.  The  Plantlet  is  Visible  in  the  Seed.     If  we  boil 
seeds  of  the  four  kinds  shown  in  Figs.  8  to  11,  or  of 
other  kinds,  in  water  until  they  are  fully  swollen,  and 
then  carefully  dissect  them,  using  a  magnifying  glass 
when  necessary,  we  may  observe  that  the  plantlet  is 
present  compactly  folded  up  in  the  seed.     Germination 
(28)   is  really  little  more  than  the  unfolding  and  ex- 
pansion of  this  plantlet.     The  plantlet  as  it  exists  in 
the  seed  is  called  the  embryo  (em'-bry-o). 

54.  The   Endosperm*   (en'-do-sperm).    From  the  sec- 
tion of  the  corn  grain  shown  in  Fig.  14,  it  appears  that 


FIG.  14.  Cross-section  of  germinating  Indian  corn  grain.  A 
endosperm;  Cot  cotyledon;  Cau  hypocotyl;  PI  plumule.  Slightly 
magnified.  (After  Frank). 

in  this  seed,  unlike  the  pea,  bean  and  pumpkin,  the 
plantlet  and  seed-case  do  not  make  up  the  whole  bulk  of 
the  seed.  The  remaining  part  shown  at  A,  consists 

*  Called    also   albumen. 


The  Plantlet.  41 

mainly  of  cells  containing  starch  grains  and  oil  drops, 
which  serve  as  food  for  the  plantlet  during  germina- 
tion, since  active  protoplasm  cannot  exist  without  nour- 
ishment (13).  In  the  pea,  bean,  pumpkin  and  other 
seeds  of  this  class,  the  food  supply,  instead  of  being 
stored  by  itself,  as  in  the  corn-grain,  is  contained 
within  the  plantlet  or  embryo — mainly  in  the  fleshy 
cotyledons.  When  the  food  supply  of  the  seed  is  sep- 
arate from  the  embryo,  as  in  corn  and  many  other  seeds, 
it  is  called  the  endosperm. 

It  is  the  food  supply  of  seeds  that  makes  them  so 
valuable  as  food  for  animals. 

55.  The  Plumule   (plu'-mule).     If  we  look  between 
the  cotyledons  of  the  bean  plantlet  (Fig.  9),  at  the  point 
of  their  union  with  the  hypocotyl,  we  may  see  a  pair 
of  tiny  leaves,  and  by  carefully  separating  these  if  need 
be,  with  the  point  of  a  pin,  we  may  discover  a  minute 
projection — the  growing  point  (66)  of  the  stem  between 
them.     These  leaves,  with  the  growing  point,  form  the 
plumule— the  terminal  bud  of  the  plantlet.     These  tiny 
leaves  become  the  first  true  leaves,   and  the  growing 
point  between  them  develops  into  the  stem  and  later 
leaves.     By   close   examination   we  may  make  out  the 
plumule  in  Figs.  8,  10  and  11.     In  the  pea  and  corn, 
it  has  already  made  considerable  growth. 

56.  Thus  we  see  that  the  plantlet  or  seedling  con- 
sists of  three  parts,  viz.,  the  hypocotyl,  the  cotyledons 
(in  some  plants  cotyledon)  or  seed-leaves,  and  the  plu- 
mule or  terminal  bud. 

57.  Chlorophyll     (chlo'-ro-phyll).      Soon    after    the 
plantlet  emerges  from  the  seed-case,  a  green  color  ap- 


42 


;  Principles  of  Plant  Culture. 


pears  in  the  parts  most  exposed  to  light.  This  is  due 
to  the  formation  within  the  cells  of  chlorophyll— the 
green  coloring  matter  of  plants.  Chlorophyll  forms 
only  in  light,  and  when  a  plant  containing  green  leaves 
is  kept  for  a  time  in  the  dark,  as  when  celery  is  banked 
up  with  earth,  the  chlorophyll  disappears  and  the  green 
parts  become  white.  The  chlorophyll  saturates  definite 
particles  of  protoplasm,  called  chlorophyll  bodies,  and 
since  the  cell-walls  and  protoplasm  are  transparent  in 
the  younger  cells,  the  chlorophyll  bodies  give  the  parts 

ch 


FIG.  15.  Showing  cross-section  through  leaf  of  Fagus  sylvatica. 
C  chlorophyll  bodies;  Ep  epidermis  of  upper  surface  of  leaf;  Ep- 
epidermis  of  lower  surface;  K  cells  containing  crystals;  PI  palis- 
ade layer;  F  vascular  bundle;  St  stoma;  I  spaces  between  the 
cells  (intercellular  spaces).  Highly  magnified.  (After  Strasburger.) 

containing  them  a  green  color.  Fig.  15  shows  the  dis- 
tribution of  the  chlorophyll  bodies  in  the  cells  of  a  por- 
tion of  a  leaf  of  the  beech.  They  appear  as  minute 
globules,  which  in  this  case  are  mostly  located  near  the 
cell-walls.  They  are  most  numerous  near  the  upper 
surface  of  the  leaf — the  part  most  exposed  to  the  sun's 
rays. 

58.  No  Food  can  be  formed  Without  Chlorophyll. 
By  the  agency  of  chlorophyll,  the  chlorophyll  bodies  ab- 


The  Plantlet.  43 

sorb  energy  in  the  form  of  light.  This  energy  the 
chlorophyll  body  uses  to  take  to  pieces  the  carbonic 
acid,  mineral  salts  and  water  absorbed  from  the  air  and 
the  soil,  and  to  recombine  them  into  foods  of  various 
kinds  which  can  be  used  by  the  protoplasm  in  making 
new  parts  and  repairing  waste  (Assimilation  (as-sim'- 
i-la-tion)).  Until  this  food  preparation  commences,  no 
new  plant  substance  has  been  formed.  It  is  true  that 
new  cell-walls  and  new  protoplasm  may  be  formed  from 
the  food  supply  of  the  seed  before  chlorophyll  appears, 
but  until  chlorophyll  is  formed,  and  food  preparation 
begins,  the  whole  plantlet  with  what- 
ever remains  of  the  seed,  when  dried, 
weighs  no  more  than  the  seed 
weighed  at  the  beginning.  The  ma- 
terial formed  for  food  is  starch,  or 
some  substance  of  similar  composi- 
tion (sugar  or  oil),  which,  after  un- 
dergomg  chemical  changes  if  need 
be,  to  render  it  soluble,  is  distrib- 
tributed  throughout  the  plant  to  be 
built  up  into  cell-walls  and  protoplasm,  or  to  be  held 
as  reserve  food  (14). 

Food  preparation  and  assimilation  are  not  necessarily 
simultaneous,  but  either  may  proceed  without  the  other. 
Only    plants    can    prepare    food    from    mineral   sub- 
stances.    The  food  of  animals  must  all  have  been  first 
formed  by  plants. 

59.  The  Sources  of  Plant  Food.  By  observing  plant- 
lets  of  the  bean  or  pumpkin  a  few"  days  after  germina- 
tion, we  may  discover  that  the  cotyledons,  which  were 


44  Principles  of  Plant  Culture. 

at  first  so  plump,  have  shriveled  to  a  mere  fraction  of 
their  former  size.  They  have  shriveled  because  the 
food  contained  by  these  parts  has  been  absorbed  by  the 
developing  plantlet.  The  patrimony  furnished  by  the 
seed  is  quickly  exhausted.  Whence  then  comes  the 
food  that  is  to  complete  the  development  of  the  plant? 
Aside  from  the  carbonic  acid  already  mentioned  (58), 
several  other  substances  are  required  to  build  up  the 
plant  structure.  These  are  almost  wholly  derived  from 
the  soil,  through  the  medium  of  the  water  absorbed  by 
the  root-hairs  (100).  They  must  all  be  dissolved  in 
the  soil  water  or  they  cannot  enter  the  plant,  for  they 
must  pass  through  the  cell-walls,  which  are  not  perme- 
able to  undissolved  solid  matter. 

60.  The    Elements   regarded  as  Essential  in  the  Food 
of  Plants  are  carbon,  hydrogen,  oxygen,  nitrogen,  po- 
tassium, calcium,  magnesium,  phosphorus,  iron,  chlorin 
and  sulfur.     Some  other  elements  that  do  not  appear 
essential  are  also  used  by  plants.  All  of  these  elements, 
so  far  as  they  serve  as  food,  are  absorbed  by  the  plant 
in  the  condition  of  chemical  compounds,  as  water,  car- 
bonic acid  and  various  nitrates,  sulfates,  etc. 

61.  The    Fart    Played  by  the  Different   Elements. 
Carbon  is  the  chief  constituent  of  vegetable  substances 
and  forms  about  half  of  their  total  dry  weight.     Plants 
obtain  their  carbon  almost  wholly  from  the  air,  in  the 
form  of  carbonic  acid  gas,  which  is  a  compound  of  car- 
bon and  oxygen.     The  leaves  absorb  and  decompose  this 
gas,  retaining  the  carbon  and  giving  off  the   oxygen 
(58).     Hydrogen  and  oxygen  are  obtained  by  the  de- 
composition of  water,  which  is  a  compound  of  hydro- 


The  Plantlet.  45 

gen  and  oxygen.  These  enter  into  the  construction  of 
nearly  all  tissues.  Nitrogen  is  one  of  the  constituents 
of  protoplasm  (13).  Most  plants  depend  upon  soluble 
nitrates  in  the  soil  for  their  nitrogen  supply,  but  those 
of  the  natural  order  to  which  the  clover  belongs*  are 
able  to  appropriate  nitrogen  from  the  air  (260).  Phos- 
phorus and  sulfur  assist  in  the  formation  of  albumin- 
ous substances;  potassium  assists  in  assimilation  (58); 
calciumf  and  magnesium,  while  uniformly  present,  seem 
to  be  only  incidentally  useful.  Iron  is  essential  to  the 
formation  of  chlorophyll  (57). 

Of  all  the  materials  obtained  by  plants  from  the  soil, 
but  three,  aside  from  water,  viz.,  nitrogen,  phosphorus 
and  potassium  (253)  are  needed  in  such  quantities  that 
the  plants  are  likely  to  exhaust  the  supply,  so  long  as 
water  is  not  deficient. 

62.  Water  is  Necessary  to  Growth.  An  adequate 
supply  of  water  is  the  most  important  condition  for  the 
well-being  of  plants,  since  it  not  only  serves  in  nutri- 
tion, but  is  the  vehicle  by  which  all  other  food  con- 
stituents are  distributed  throughout  the  plant.  Com- 
paratively few  soils  are  so  poor  as  to  be  incapable  of 
producing  good  crops  when  sufficiently  supplied  with 
water,  while  the  richest  soils  are  unproductive  when 
inadequately  supplied  with  it.  Much  of  the  benefit  of 
manuring  undoubtedly  comes  from  the  increased  ca- 
pacity it  gives  the  soil  for  holding  and  transmitting 
water  (92). 

*  Leguminosae. 

t  Lime  which  is  a  compound  of  calcium,  appears  to  be  essen- 
tial to  the  fruiting  of  some  plants,  as  the  peanut,  while  detri- 
mental to  the  fruiting  of  others,  as  the  cranberry  and  huckle- 
berry. 


46  Principles  of  Plant  Culture. 

The  supplying  of  food  material  is  not  the  only  office 
performed  by  water  in  the  plant.  The  unfolding  and 
expansion  of  the  plantlet  is  largely  due  to  a  strong  ab- 
sorptive power  for  water  possessed  by  the  protoplasm 
within  the  cells.  This  force  causes  all  living  parts  of 
plants  to  be  constantly  saturated  with  water.  Indeed, 
it  distends  the  elastic  cell-walls  with  water  until  they 
are  like  minute  inflated  bladders.  The  pressure  thus 
set  up  aids  in  unfolding  the  different  parts  from  their 
snug  resting-place  within  the  seed-case  and  enables  the 
plantlet  to  stand  erect.  Growth  by  cell  division,  it  is 
true,  begins  rather  early  in  the  germination  process, 
but  this  cannot  take  place  unless  the  cells  are  first  dis- 
tended with  water  (29).  A  sufficient  amount  of  water 
is  absolutely  necessary,  therefore,  to  growth  in  plants. 
Foliage  wilts  in  dry  weather  because  the  roots  are  un- 
able to  supply  enough  water  to  properly  distend  the 
cells ;  growth  is  impossible  in  plants  of  which  the  foliage 
is  wilted.  When  the  water  supply  is  abundant,  on  the 
other  hand,  and  the  absorptive  power  of  the  roots  is 
stimulated  by  a  warm  soil  (101),  the  pressure  within 
the  cells  often  becomes  sufficient  to  force  water  from 
the  edges  and  tips  of  leaves.  The  drops  of  water  that 
so  often  sparkle  on  foliage  in  the  sunlight  of  summer 
mornings,  commonly  mistaken  for  dew,  are  usually 
excreted  from  the  leaves.  In  young  plants  of  the  cala- 
dium,  water  is  sometimes  ejected  from  the  leaf-tips 
with  considerable  force. 

The  water  of  plants  is  almost  wholly  absorbed  by  the 
root-hairs  (100),  the  leaves  having  no  power  to  take  up 
water,  even  in  wet  weather.  The  water  of  plants,  with 


The  Plantlet.  47 

its  dissolved  constituents,  is  commonly  called  sap,  ex- 
cept in  fruits,  when  it  is  usually  called  juice. 

63.  How  Food  Materials  are  Distributed  through 
the  plant.  If  we  drop  a  bit  of  aniline  blue  into  a  glass 
of  clear  water,  it  will  not  retain  its  form  and  size,  but 
infinitely  small  particles  will  become  detached  and  move 
about  to  all  parts  of  the  water  in  which  it  dissolves. 
This  movement  will  not  stop  until  the  bit  has  entirely 
disappeared,  and  until  every  part  of  the  water  contains 
exactly  as  much  of  the  aniline  blue  as  every  other  part. 
This  equal  distribution  of  the  soluble  material  takes 
place  in  response  to  the  law  of  diffusion,  that  tends  to 
cause  any  soluble  substance  to  become  equally  distrib- 
uted throughout  the  liquid  in  which  it  is  placed.  The 
liquid  in  the  meantime  may  remain  stationary.  The 
process  would  be  the  same  if  we  were  to  put  in  a  very 
small  quantity  of  each  of  several  soluble  substances  at 
the  same  time.  The  movements  of  one  of  these  sub- 
stances would  not  interfere  much  with  those  of  the 
others. 

If  we  could  remove  some  of  the  dissolved  aniline  blue 
from  the  water  in  one  part  of  the  glass,  it  would  follow 
that  the  dissolved  aniline  blue  would  move  from  the 
other  parts  toward  this  point,  and  if  the  removal  were 
continuous,  slow  currents  would  move  in  this  direction 
from  all  other  parts  of  the  glass. 

We  may  now  understand  how  the  materials  from 
which  the  plant  is  built  up  are  distributed  to  its  dif- 
ferent parts.  The  water  absorbed  by  the  root-hairs 
(100)  is  not  chemically  pure,  but  holds  in  solution  small 
quantities  of  various  soluble  matters  contained  by  the 


48 


Principles  of  Plant  Culture. 


soil,  some  of  which  are  used  by  the  plant  in  growth. 
As  these  useful  matters  are  removed  from  the  water  of 
the  cells,  to  be  formed  into  food  (58),  the  supply  is 
replenished  from  the  soil,  not  through  any  power  of 
selection  possessed  by  the  plant,  but  in  accordance  with 
the  law  of  diffusion.  In  like  manner,  the  food  formed 
by  the  chlorophyll  (58)  finds  its  way  to  the.  growing 
parts.  Soluble  matters  not  used  by  the  plant  are  not 
taken  in  to  the  same  extent  as  those  that  are  needed, 
because  their  distribution  is  less  disturbed. 

The  distribution  of  soluble  matter  in  the  plant  is  also 
promoted  by  transpiration   (74). 

SECTION  IV.     THE  INNER  STRUCTURE  OF  THE  PLANTLET. 

Thus  far,  we  have  considered  the  plantlet    mainly 
from  the  outside.     Before  going  farther,  it  is  well  to 
learn   also   something   of   its 
-Dinner    structure.      We    have 
Pal  seen    that   all    parts    of    the 
plant  are  made  up   of  cells 
(12)  and  that  these  cells  dif- 
fer in  form  and  office  in  the 
different  parts.     The  cells  of 
the    leaf,    for    example,    are 
different  in  shape  and  in  the 
use  they  serve  to  the  plant, 
from     those     of     the     stem, 


FIG.     17.       Showing     section  „  .      . 

through     leaf     of     Oldenburgh    nOWCr   or  iruit 
apple.       Ep.      epidermis;     Pal 
pali 
s 


.  .  . 

alisade    cells;     I    intercellular        64.   The    Epidermis     (ep'-l- 
paces.     Highly  magnified.    See 

lso  Figs.  13  and  20.  der-mis)  .     The  plant  is  cov- 

ered by  thin,  translucent   skin  that  extends   over  the 


The  Inner  Structure  of  the  Plantlet.  49 

entire  surface  of  the  leaves,  stem  and  root,  called  the 
epidermis  (Fig.  17  Ep.)  This  skin  is  formed  of  com- 
paratively thick-walled  cells  and  serves  to  protect  the 
more  delicate  parts  within.  It  may  be  readily  with- 
drawn in  some  plants,  as  from  the  leaves  of  the  live- 
forever*  and  echeveriaf  and  young  stems  of  the  plum. 
The  exposed  surface  of  the  epidermis  of  the  leaves, 
fruit  and  young  stems  of  many  plants  is  transformed 
into  a  layer  that  is  more  or  less  impervious  to  water, 
called  the  cuticle  (cu'-ti-cle),  which  serves  to  restrict 
evaporation  (74).  To  further  protect  the  parts,  a 
layer  of  wax  (bloom)  is  sometimes  secreted  upon  the 
outside  of  the  cuticle,  as  in  the  fruit  of  many  varieties 
of  the  plum  and  grape. 

Root-hairs  (100)  and  the  hairs  and  bristles  on  the 
stems  and  leaves  of  many  plants  are  cells  of  the  epi- 
dermis elongated  outward.  The  epidermis  must  not  be 
confounded  with  the  bark.  It  is  replaced  by  bark  in 
the  older  stems  of  woody  perennial  plants. 

To  give  further  strength  to  the  upper  surface  of  the 
leaf,  the  first  two  or  three  tiers  of  cells  beneath  the  epi- 
dermis on  the  upper  side  are  usually  placed  endwise, 
(palisade  cells,  Figs.  17,  15  and  3).  The  hardier  varie- 
ties of  apple,  as  the  Oldenburgh  (Duchess),  have  more 
numerous  and  more  crowded  palisade  cells  than  less 
hardy  varieties.  Compare  the  palisade  cells  of  a  leaf 
of  the  Oldenburgh  apple  (Fig.  17),  with  those  of  Fig. 
3,  which  shows  a  section  from  a  leaf  ^of  a  tender  variety 
of  apple. 

*Sedum  telephium.          f  Cotyhdon. 


50  Principles  of  Plant  Culture. 

65.  Stomata   (stom'-a-ta).     Minute  openings  through 
the  epidermis  occur  in  the  leaves  and  young  stems  of 

land  plants, 
connecting 
intercellular 
spaces  (I, 
Fig.  17)  with 
the  external 
air.  These 
openings  are 
each  bounded 
by  a  pair  of 
g  u  a  r  d-cells, 
called  stom- 

FIG.    18.     Showing  stomata   (st.)    on   leaf  of   the   ata         (singU- 
garden  beet.     Moderately  magnified.     (After  Frank 
and  Tschirch).     See  also  Figs.    15,    19  and   22.  Jaj*       S  t  0  m  a 

(sto'-ma),  Figs.  18  and  19,  St).  They  are  chiefly  found 
on  the  lower  side  of  leaves,  and  are  extremely  numer- 
ous, but  are  too  small 
to  be  seen  without  the  *p  ^J} 
microscope.  An  aver- 
age apple  leaf  has 
been  computed  to 
contain  about  150,000 
stomata  to  the  square 
inch  on  its  lower 
surface.  These  cells, 
which  are  attached 
together  only  at  their  ends  and  are  thickened  on  their 
inner  side,  become  bent  or  crescent-shaped  when  turgid, 


FIG.  19.     Showing   tomato   (st.)    on  leaf 
Oldenburgh   apple.    Highly    magnified. 


The  Inner  Structure  of  the  Plantlet.  51 

thus  forming  an  opening  through  which  water  escapes 
and  carbonic  acid  enters  the  leaf. 

These  guard-cells  are  delicately  balanced  valves 
which  are  extremely  sensitive  to  external  influences. 
They  are  open  in  strong  light,  but  usually  closed  in 
darkness  and  when  the  leaves  are  wet.  They  become 
turgid  as  the  whole  leaf  is  turgid,  thus  protecting  the 
tissues  from  an  excess  of  water.  Conversely,  as  the  leaf 
loses  water  the  guard-cells  become  less  turgid,  protect- 
ing the  tissues  from  too  great  a  loss  of  water.  In  this 
manner  the  plant  regulates  the  amount  of  water  in  its 
tissues  according  to  its  requirements.  The  slightly- 
raised  spots  or  dots  on  the  smooth  bark  of  the  young 
shoots  of  many  woody  plants,  (lenticels  (len'-ti-cels)), 
serve  a  similar  purpose  to  the  stomata. 

66.  The   Growing    Point.     At   the  tip   of  the  stem 
and  just  behind  the  tip  of  the  root,  is  a  group  of  cells 
forming  the  so-called  growing  point.     These  cells   di- 
vide very  rapidly  during  the  growing  season,  and  from 
them  all  other  kinds  of  cells  are  evolved. 

67.  The  Vascular  (vas'-cu-lar)   Bundles.*    While  the 
plantlet  remains  within  the  seed-case,  it  consists  largely 
of  cells  more  or  less  cubical  or  globular  in  outline.     But 
germination    scarcely    commences    before   some   of   the 
cells  begin  to  increase  greatly  in  length  without  a  cor- 
responding   increase    in    thickness. f     These    elongated 
cells    form   in   groups   or   bundles    (vascular   bundles) 
that  extend  lengthwise  through  the  stem  and  roots,  and 

*  Also    called    flbro-vascular    bundles. 

t  Cells  of  the  former  class,  i.  e.,  those  that  retain  their  globu- 
lar shape,  are  called  Parenchyma  (pa-ren'-chy-ma),  and  those  of 
the  latter  class  prosenchyma  (pro-sen'-chy-ma)  (Fig.  20).  Fig.  17 
shows  parenchyma  cells  from  the  appple  leaf. 


52 


Principles  of  Plant  Culture. 


since  the  individual  cells  overlap  and  are  in  intimate 
contact,  they  form  threads  or  fibres.  These  fibres  serve 
the  double  purpose  of  giving  strength  to  the  plant  and 
conducting  water,  with  its  dissolved  food  materials,  to 
the  different  parts.  By  the  absorption  of  the  ends  of 
some  of  the  cells,  tubes  (ducts),  of 
very  considerable  length  are  formed. 
In  other  cells  of  vascular  bundles, 
the  walls  are  much  thickened  and 
strengthened  by  woody  deposits. 
These  groups  or  bundles  of  fibres 
and  ducts  divide  and  subdivide  in 
the  leaves,  forming  the  so-called 
veins  and  veinlets.  In  the  roots 
they  divide  in  a  similar  manner,  ex- 
tending lengthwise  through  all  the 
branches  and  branchlets. 

FIG.   20.   Prosenchy-        Fig-    20    shows    a    longitudinal    S6C- 

SaryeellSHi§rniy  mag£  tion  of  a  vascular  bundle  of  the  rye 
and6  TscwSho  *"""*  plant  and  Fig.  21  shows  a  cross-sec- 
tion of  a  vascular  bundle  of  the  sunflower. 
\  The  threads  in  the  stalk  of  Indian  corn  and  the  leaf- 
stem  of  the  plantain*  furnish  examples  of  well-defined 
vascular  bundles;  in  most  stems  the  vascular  bundles 
are  less  clearly  defined.  In  woody  stems  they  are 
closely  crowded,  which  gives  the  wood  its  firm  texture. 
In  some  woody  plants,  as  the  grape  and  the  elder,f  a 
cylinder  extending  through  the  center  of  the  stem  is 
free  from  vascular  bundles,  forming  the  pith.  The 
young  stems  of  asparagus,  the  ball  of  the  kohl-rabi  and 

*  Plantago.  t  Sambucus. 


The  Inner  Structure  of  the  Plantlet.  53 

the  roots  of  turnip  are  "stringy"  when  the  cells  of 
their  vascular  bundles  become  thickened  by  the  de- 
posit of  woody  ma- 
terial in  them. 

68.  The  Cam- 
bium (cam'-bi-um) 
Layer.  In  most 
plants  having  two 
or  more  cotyle- 
dons (45),  a  layer 
of  cells  in  a  state 
of  division  (15) 

FIG.  21.    Showing  cross-section  of  a  vas-          .          ,  ,, 

cular  bundle  of  the  sunflower.  (Helian-  CXlStS  between  U16 
thus  annuus).  Highly  magnified.  (After  ,  n  ,  ., 

Pranti.)    See  also  Fig.  22.  bark  andthewood, 

called  the  cambium  or  cambium  layer  (Fig.  22).  It 
is  in  this  layer  that  growth  in  diameter  of  the  stem  oc- 
curs (70).  The  bark  of  plants  having  the  cambium 
layer  separates  readily  from  the  wood  at  times  when 
growth  is  rapid,  because  the  walls  of  the  newly-formed 
cambium  cells  are  extremely  thin  and  tender.  The 
slimy  surface  of  growing  wood,  whence  the  bark  has 
just  been  removed,  is  due  to  the  protoplasm  from  the 
ruptured  cambium  cells.  In  plants  having  more  than 
one  cotyledon,  the  cambium  line  is  usually  readily  dis- 
cerned in  cross-sections  of  the  stem — though  it  is  rather 
more  distinct  and  the  bark  is  more  readily  separable  in 
woody  than  in  herbaceous*  stems.  In  the  latter,  the 
part  within  the  cambium  line  corresponds  to  the  wood 
of  woody  stems,  and  that  outside  of  it  corresponds  to 
the  bark. 


*  Herbaceous  stems  are   those  that  do  not  have   the  hard,   firm 
texture  of  wood,  as  the  potato,  rhubarb,  etc. 


54 


Principles  of  Plant  Culture. 


69.  Portions  of  Cambium  from  different  plants  may 
Unite  by  Growth.  If  a  section  of  cambium  from  one 
part  of  a  plant  is  closely  applied  to  the  cambium  of  an- 
other part  of  the  same  plant,  or  of  another  closely  re- 
lated plant,  the  two  portions  of  cambium  may  unite  by 

st  ^     f 


^fV- -W 


FIG.  22.  Showing  transverse  section  of  corner  of  a  bean  stem 
(Vicia  faba).  C  cambium  layer;  e  epidermis;  Cu  cuticle;  St 
stoma.  The  dark,  oval-shaped  spots,  extending  both  sides  of  the 
cambium  layer  are  the  vascular  bundles;  W  wood  cells  of  the 
vascular  bundles.  Moderately  magnified.  (After  Potter.) 

growth,  a  fact  of  great  importance  in  horticulture  since 
it  renders  grafting  possible  (383).  Plants  having  no 
cambium  layer  (70)  cannot,  as  a  rule,  be  grafted,  be- 
cause their  stems  have  no  layer  of  dividing  cells — the 
only  cells  that  unite  by  growth. 

70.  How  Stems  Increase  in  Diameter.  There  is  no 
cambium  layer  in  plants  having  but  one  cotyledon 
(45),  of  which  Indian  corn,  the  grasses  and  palms 
are  examples.  In  such  plants  there  is  no  clear  separa- 


The  Inner  Structure  of  the  Plantlet.  55 

tion  between  bark  and  wcod;  the  stem  enlarges  for  a 
time  by  growth  throughout  its  whole  diameter,  after 
which  it  ceases  to  expand.  ; 

In  plants  having  two  or  more  cotyledons,  however, 
additions  to  the  bark  cells  are  constantly  being  made 
during  the  growing  season  on  the  outside  of  the  cam- 
bium layer,  as  are  additions  to  the  wood  cells  on  the  in- 
side of  it  (Fig.  22).  It  follows  that  growth  of  the  bark 
takes  place  on  its  inner  surface  and  growth  of  the  wood 
takes  place  on  its  outer  surface.  This  explains  the  ver- 
tically-furrowed appearance  of  the  bark  of  old  trees 
which  is  being  constantly  split  during  the  growing 
season  by  the  forming  layer  within.  It  also  explains 
the  ringed  appearance  of  a  cross-section  of  a  woody 
stem.  A  new  ring  of  wood  is  formed  each  season  on 
the- outside  of  that  previously  formed,  and  the  line  sep- 
arating the  rings  marks  the  point  where  growth  in 
autumn  ceased  and  was  renewed  the  following  spring. 
The  age  of  a  given  part  of  the  stem  of  a  woody  plant 
is  approximately  indicated  by  the  number  of  its  wood 
rings.* 

71.  The  Vital  Part  of  Woody  Stems  in  plants  hav- 
ing more  than  one  cotyledon  (45)  is  limited  to  a  rather 
thin  layer  of  bark  and  wood,  of  which  the  cambium 
(68)  forms  the  center.  The  cells  of  the  so-called  heart- 
wood  and  those  of  the  dry  and  furrowed  outer  bark, 
have  lost  their  protoplasm,  and  hence  are  no  longer 
alive,  though  they  serve  a  useful  purpose  in  adding 
strength  and  protection  to  the  vital  layer.  The  heart- 

*  More  than  one  wood  ring  is  sometimes  formed  in  a  season. 
If  growth  ceases  during  the  summer  from  severe  drought  or  other 
cause,  and  is  renewed  the  same  season,  an  extra  ring  is  formed. 


56 


Principles  of  Plant  Culture. 


wood  of  a  tree  may  largely  decay  without  materially 
interfering  with  the  vital  processes   (Fig.  23). 

72.  The  Healing  of  Wounds.  Cambium  cells  ex- 
posed to  the  air  by  partial 
or  complete  removal  of  the 
bark,  soon  perish,  as  a  rule, 
hence  growth  ceases  in  a 
part  of  the  stem  thus  in- 

||y'  'jjJilUtK  Jured.  The  uninjured  cam- 
>M  #?®3ffil5lk  bium  cells  on  the  borders 
of  the  wound  may,  however, 
by  division  (15),  form  a 
cushion  of  new  material  that 
gradually  extends  over  the 
injured  part.  A  new  cam- 
bium layer  may  thus  •  be 
formed  over  the  wound  if  it 
be  not  too  large,  so  that 
growth  of  the  stem  may  be 
resumed  at  this  place.  The 
same  process  occurs  when  a 
branch  is  cut  off  near  its 
union  with  the  stem.  The 
wound,  if  not  too  large,  is 
"healed"  by  new  growth 
poplar  "tree  from  the  adjacent,  uninjured 
cambium  cells  (Fig.  24). 
The  younger  the  uninjured 
tissues  are  the  more  rapid  is  the  healing.  In  planted 
cuttings,  the  uninjured  cambium  cells  at  the  base  form 
the  callus  (cal'-lus)  by  continued  division  (Fig.  25). 


The  Water  of  Plants  and  Its  Movements.        57 

Exposure  of  the  bark  to  undue  heat  or  cold  may  de- 
stroy the  cambium,  causing  sunscald  (185). 

In  periods  of  very  rapid  growth,  when  the  cambium 
cells  are  unusually  active,  large  areas  of  bark,  even  ex- 
tending clear  around  the  stem  and  as 

deep   as   the   cam- 

bium   layer,    may 

sometimes    be    re- 

moved   from   trees 

without     destroy- 

ing their  life,  pro- 

vided the  recently- 

formed  wood  layer 

is     not     injured 

(70).     In  this  case, 


eaus 
tins  off  a  branch  (A).        ^    ^    ^    Qf  ~™ 

cambium  that  remains  on  the  surface  of  the  wood 
promptly  change  to  bark  cells,  hence  a  new  bark  layer 
forms  over  the  exposed  surface  the  same  season. 

Several  successive  crops  of  bark  are  sometimes  re- 
moved from  the  trunk  of  the  cork  oak,*  but  in  this 
case,  the  cambium  layer  is  usually  not  injured. 

SECTION  V.     THE  WATER  OF  PLANTS  AND  ITS 
MOVEMENTS. 

73.  Plants  Contain  Large  Amounts  of  Water.  We 

have  seen  that  the  cell-walls  of  living  plants  are  con- 
stantly saturated  with  water  (62),  and  that  the  cells  of 
the  growing  parts  are  always  more  or  less  distended 
with  it.  The  proportion  of  water  contained  in  living 

*  Quercu*  suber. 


58  -  Principles  of  Plant  Culture. 

plants  is  generally  very  large.  In  the  root  of  the  tur- 
nip and  in  some  fruits,  it  may  exceed  ninety  per  cent 
of  the  whole  weight.  It  is  greatest  in  young  plants 
and  in  the  younger  and  growing  parts  of  older  plants. 
The  proportion  of  water  is  not  constant  in  the  same 
plants,  but  varies  somewhat,  with  the  water  content  of 
the  soil  and  with  meteorological  conditions. 

74.  Transpiration  (trans-pi-ra'-tion) .  The  water  of 
plants  passes  off  more  or  less  rapidly  from  parts  ex- 
posed to  the  air— usually  as  an  invisible  vapor.  This 
invisible  escape  of  water  from  plants  is  called  trans- 
piration. It  is  mainly  due  to  evaporation  of  water 
from  the  plant,  the  same  as  takes  place  from  other  moist 
material.  But  fluctuations  occur  in  the  amount  of 
transpiration  from  living  plants  that  do  not  occur  in 
dead  organic  material  under  similar  conditions.  For 
example,  transpiration  is  more  rapid  in  light  than  in 
darkness,  because  the  stomata  (65)  are  open  in  the  light 
and  thus  facilitate  the  escape  of  water  from  the  inter- 
cellular spaces.  Plants  poorly  supplied  with  nourish- 
ment transpire  more  freely  under  the  same  conditions 
than  those  well  supplied.  The  amount  of  transpiration 
varies  greatly  in  different  plants  and  depends  upon  the 
leaf  surface,  the  nature  of  the  epidermis  and  cuticle 
(64),  the  number  of  stomata  (65),  etc.  Some  plants, 
as  purslane,  the  sedums,  cacti,  etc.,  have  special  water- 
storing  tissue,  from  which  transpiration  is  extremely 
slow. 

Experiments  indicate  that  the  transpiration  from 
most  leaves  is  between  one-third  and  one-sixth  as  much 
as  the  evaporation  from  an  equal  area  of  water.  When 


The  Water  of  Plants  and  Its  Movements.         59 

we  take  into  account  the  immense  leaf  surface  of  a  large 
tree,  it  is  evident  that  the  aggregate  transpiration  must 
be  very  great,  as  is  often  illustrated  by  the  dwarfing  in- 
fluence of  trees  upon  adjacent  crops  in  dry  weather 
(Fig.  26).  Transpiration  is  much  more  rapid  during 


FIG.  26.  Showing  how  a  spruce  hedge  dwarfs  an  adjacent  corn 
crop  in  dry  weather. 

dry  than  during  wet  weather,  and  in  the  rare  atmos- 
phere of  high  altitudes  than  in  the  denser  atmosphere 
of  low  lands. 

Excessive  transpiration,  as  occurs  in  very  dry 
weather,  is  detrimental  to  plants,  since  it  reduces  the 
water  pressure  within  the  cells  below  the  point  where 
healthful  growth  can  take  place  (62)  ;  but  normal 
transpiration,  i.  e.,  not  sufficient  in  amount  to  interfere 
with  healthful  growth,  is  doubtless  beneficial,  since  it 
aids  in  carrying  food  materials  from  the  soil  into  the 
leaves  (58).  For  this  reason,  plants  native  to  regions 
having  a  rather  dry  atmosphere,  do  not  thrive  in  green 
houses  unless  abundant  ventilation  is  given  to  encour- 
age transpiration. 

75.  Trees  are  Detrimental  to  Crops  in  their  vicinity 
not  only  by  the  shade  they  cause,  but  also  by  their  e*- 
hausting  effect  upon  the  soil  moisture  in  dry  weather. 


60  Principles  of  Plant  Culture. 

The  area  affected  by  a  group  of  trees  is  often  much 
larger  than  is  supposed.  Fig.  26  shows  how  an  ever- 
green hedge  may  restrict  the  growth  of  corn  in  an  ad- 
joining field.  We  should  not  infer  from  this,  however, 
that  trees  are  on  the  whole  detrimental  to  agriculture. 
They  serve  many  useful  purposes. 

Experimental  crops  intended  to  be  comparable  with 
each  other  should  not  be  planted  near  growing  trees. 

76.  The    Brittleness   of    Young    Plant   Tissues    de- 
pends upon  the  degree  of  water  pressure  within  the 
cells.     Foliage  is  usually  most  brittle  during  the  morn- 
ing and  least  brittle  during  the  latter  part  of  the  day, 
because  transpiration  is  most  active  during  the  warm 
hours  of  the  day.    Lettuce  and  other  salad  plants  are, 
therefore,  apt  to  be  more  crisp  and  tender  when  cut 
in  the  morning.     Tobacco,   in   which  breaking  of  the 
leaves  is  harmful,  is  preferably  cut  in  the  afternoon. 
Young  hoed  crops  are  generally  less  injured  by  the 
smoothing  harrow  in  the  afternoon  than  in  the  morning, 
and  grass  intended  for  hay  usually  dries  soonest  when 
cut  in  the  afternoon.     Lawn  grass  generally  cuts  easier 
in  the  morning  than  in  the  afternoon. 

Slightly  withered  vegetables  may  have  their  crispness 
partially  restored  by  soaking  them  in  water  for  a  time. 

77.  The  Evaporation  Current.     Since  the  water  of 
plants  is  taken  in  from  the  soil  through  the  root-hairs 
(100),  and  escapes  more  or  less  rapidly  by  transpiration 
(74),  it  is  clear  that  in  leafy  plants  a  current  of  water 
must  pass  from  the  roots  through  the  stem  and  branches 
into  the  leaves,  and  that  the  rate  of  this  current  will 
depend  much  upon  the  rate  of  transpiration  from  the 


The  Water  of  Plants  and  Its  Movements.        61 

foliage.  When  the  soil  moisture  is  reduced  and  trans- 
piration is  excessive,  this  upward  current  of  water  is 
not  always  sufficient  to  maintain  the  normal  pressure 
within  the  cells  (62),  hence  the  foliage  wilts,  or  the 
leaves  roll  up,  as  in  Indian  corn  and  some  other  plants 
of  the  grass  family.  This  current  passes  chiefly  through 
the  younger  vascular  bundles  (67),  which  in  trees  con- 
stitute the  so-called  sap-wood,  since  the  cells  of  these 
are  less  obstructed  by  woody  deposits  than  those  of 
other  tissues. 

The  physical  forces  that  cause  the  soil  water  to  rise 
to  the  tops  of  tallest  trees  are  not  well  understood,  but 
osmosis*  (os-mo-sis)  and  the  pull  produced  by  the  evap- 
oration of  water  from  the  leaves,  play  important  parts. 

78.  The  Flow  of  Sap  in  Spring.  In  the  temperate 
zones,  evaporation  from  the  leafless  stems  of  deciduous 
trees  and  shrubs  nearly  ceases  during  winter.  The  por- 
tion of  the  roots  of  these  plants,  however,  that  lies  be- 
low the  frost  line,  continues  to  absorb  water,  which 
gradually  accumulates  in  the  stems  and  branches.  On 
the  return  of  spring  weather,  the  rise  in  temperature 
causes  expansion  of  the  tissues  of  the  stem,  as  well  as 
of  the  air  and  water  within  it.  This  creates  so  much 
pressure  in  some  trees  and  shrubs  that  water  flows 
freely  from  wounds  in  the  wood,  bearing  with  it,  of 
course,  the  materials  it  holds  in  solution.  This  hap- 
pens when  we  tap  a  sugar  maple  tree  in  spring.  Alter- 


*  Osmosis  is  the  tendency  that  causes  two  liquids  of  different 
densities  to  mix  with  each  other  when  separated  by  a  permeable 
membrane.  The  less  dense  liquid  tends  to  flow  into,  a  denser  one 
with  a  force  corresponding  to  the  difference  in  their  densities. . 
Cell  contents  are.  denser  than  soil  water,  hence  the  latter  tends 
to  flow  into  the  cells,  and  thus  to  rise  in  the  plant. 


62  Principles  of  Plant  Culture. 

nate  rise  and  fall  of  temperature  increases  the  flow  of 
sap,  because  with  each  contraction,  new  supplies  of 
water  or  air  are  drawn  into  the  stein,  .and  thus  the  pres- 
sure is  maintained.  Sap  ceases  to  flow  on  the  opening 
of  the  buds,  because  transpiration  from  the  foliage  (74) 
quickly  relieves  the  abnormal  pressure. 

The  popular  idea,  that  the  flow  of  sap  in  spring  is 
due  to  a  rapid  rise  of  water  through  the  stem  at  that 
season,  is  erroneous.  The  sap  is  really  rising  through  the 
stem  much  faster  in  midsummer  than  in  early  spring. 

79.  The  Current  of  Prepared  Food  (elaborated sap). 
The  food  of  the  protoplasm  in  the  different  parts  of 
the  plant  is  prepared  almcs,t  wholly  in  the  leaves  (120). 
We  know,  however,  that  growth  occurs  in  the  stem  and 
roots  as  well  as  in  the  leaves.  It  is  clear,  therefore, 
that  when  the  stem  and  roots  are  growing,  a  movement 
of  food  matter  must  occur  from  the  leaves  into  these 
organs.  This  movement  may  be  demonstrated  by  a 
simple  experiment.  If  a  notch  deep  enough  to  pass 
through  the  bark  and  a  little  into  the  wood,  is  cut  into 
the  stem  of  any  of  our  common  woody  plants  during 
spring  or  summer,  a  callus  or  cushion  of  new  cells  (72) 
will  soon  form  on  the  upper  side  of  the  notch,  but  not 
on  the  lower,  showing  that  the  material  from  which  new 
cells  are  formed  is  passing  downward.  Close  examina- 
tion will  show  that  this  callus  forms  just  outside  the 
union  of  the  bark  and  wood.  In  all  plants  having  more 
than  one  cotyledon  (45),  this  current  is  through  the 
sieve  tubes  in  the  inner  layers  .of  the  bark.  The  pre- 
pared food  matter  is  dissolved  in  the  water  that  satu- 
rates the  cell-walls,  and  passes  from  the  leaves  to  other 
parts  of  the  plant  by  diffusion  (63). 


The  Water  of  Plants  and  its  Movements.        63 

80.  Killing  Trees  by  Girdling.     To  destroy  the  life 
of  a  tree  that  can  not  be  conviently  removed,  we  girdle 
it  by  cutting  a  notch  about  the  trunk  beneath  the  lowest 
branch.     This  cuts  off  the  downward  food  current  and 
so  starves  the  protoplasm  of  the  roots.     If  the  notch  is 
made  after  the  leaves  have  expanded  in  spring,  and  ex- 
tends only   through  the  bark,  the  leaves  may   remain 
fresh  for  several  weeks,  for  the  transpiration  current 
passing    through    the    sap-wood     (77)    may    continue. 
Since  the  roots  receive  no  nourishment,  however,  they 
will  soon  cease  to  grow  and  will  usually  die  from  starva- 
tion before  the  following  spring.     If  the  notch  is  cut 
deep  enough  to  reach  through  the  sap-wood,  thus  cut- 
ting off  both  the   ascending  and   descending   currents, 
death  of  the  tree  soon  follows. 

81.  Root  Starvation  may  occur  Without  Girdling. 
In   seasons  of  extreme   drought,   when   the   leaves   are 
poorly  supplied  with  crude  food  materials  from  the  soil, 
the  amount  of  prepared  food  may  be  so"  meagre  that 
the  food  current  will  be  exhausted  before  it  reaches  the 
roots.     In  such  cases  the  roots  perish,  and  the  tree  is 
found  dead  the  following  spring.     This  most  frequently 
occurs  with  trees  on  poor  soil,  that  have  suffered  from 
insect  attacks  as  well  as  from  a  dearth  of  water.     It 
often    occurs   also   in   recently-transplanted   trees   that 
fail  to  make  satisfactory  growth  the  first  season. 

82.  To  Destroy  the  most  persistent  Weeds  we  starve 
the  roots  by  preventing  all  leaf  growth  (339). 

83.  Restriction   of   the   Growth   Current    Promotes 
Fruitfulness  by  causing  an  accumulation  of  prepared 
food  in  the  stem  and  branches  (134  B). 


64  Principles  of  Plant  Culture. 

84.  The    Storage    of    Reserve    Food.      In    healthy 
plants,  food  is  usually  prepared  faster  than  it  is  con- 
sumed by  growth.     The  surplus  may  be  in  the  form  of 
starch,  as  in  the  potato    (Fig.   16),  wheat  and  sago; 
sugar,  as  in  the  sugar  cane,  sugar  maple  and  beet;  or 
oil,  as  in  cotton  seed,  flax  seed  and  rape.     Aside  from 
the  seeds,  which  are  always  stocked  with  reserve  food, 
certain  plants  living  more  than  one  year  as  the  potato, 
beet,  onion,  kohl-rabi,  etc.,  have  special  accumulations 
of  food  in  certain  parts,  and  the  parts  of  plants  that 
contain  such  reserve  food  are  most  valuable  as  food  for 
man  or   animals.     The  proportion  of  starch  stored  in 
potato  tubers  is  not  constant,  hence  the  food  value  of 
different    samples   of   potatoes   may   vary   greatly.     In 
woody  plants,  the  surplus  food  is  more  evenly  distrib- 
uted through  the  different  parts,  though  the  older  leaf- 
bearing  wood  is  usually  best  supplied. 

85.  Plants  Use  their  Reserve  Food  in  the  produc- 
tion of  flowers  and  seeds  (134  A),  and  in  repairing  dam- 
ages, as  the  healing  of  wounds  (72),  or  the  replacement 
of  leaves   destroyed   by  insects  or  otherwise.     Annual 
plants    (337)    expend  all  their  reserve  food  in  flower 
and  seed  production  and  then  perish  as  soon  as  the  seed 
is  ripe.     Biennial  plants  devote  the  first  season  of  their 
life  to  storing  an  abundant  food  supply,  which  is  ex- 
pended in  flower  and  seed  production  the  second  year. 
Our  seed  crops,  as  oats,  corn,  peas  and  beans,  are  mostly 
annuals;  our  vegetables  other  than  seeds,  as  beets,  cab- 
bage, parsnips  and  celery,  are  mostly  biennials.     Peren- 
nial plants,  in  normal  condition,  expend  only  a  part  of 
their  reserve  food  in  any  one  season  for  the  production 


The  Root  and  the  Soil.  65 

of  flowers  and  seeds,  withholding  the  remainder  for 
nourishment  through  the  winter  and  to  develop  leaves 
the  following  spring.  The  reserve  food  in  dormant  cut- 
tings (358)  enables  them  to  form  roots  and  expand 
their  buds. 

SECTION  VI.     THE  ROOT  AND  THE  SOIL. 

With  the  out-door  cultivator,  the  part  of  the  plant 
environment  that  lies  beneath  the  soil  surface  is  more 
under  control  than  the  part  that  lies  above  it.  He  can 
do  little  to  change  the  composition  or  temperature  of 
the  air  or  the  amount  of  sunlight;  he  may  do  much  to 
influence  the  fertility,  the  texture,  the  drainage  and  the 
aeration  of  the  soil.  A  knowledge  of  the  roots  of 
plants  and  of  the  soil  in  which  they  grow  and  feed,  is, 
therefore,  of  the  utmost  practical  importance. 

86.  The  Office  of  the  Root.  The  roots  of  laud  plants 
serve  (a)  to  anchor  the  plant  in  the  soil,  enabling  the 
stem  or  stems  of  erect  species  to  grow  upright,  and  (b) 
to  supply  the  plant  with  water  with  its  dissolved  food 
materials  (62). 

87.  The  Root  Originates  in  the  Stem.    As  we  have 
seen,   the  primary   root    develops    from  .the    lower   or 
"root-end"  of  the  hypocotyl   (44).     But  lateral  roots 
may  develop  freely  from  other  parts  of  the  stem.     If 
we  examine  the  base  of  the  stem  of  a  plant  of  Indian 
corn  a  few  weeks  after  planting,  we  may  see  that  the 
main  roots  start  above  the  point  at  which  the  stem  was 
originally  attached  to  the  seed;  and  if  we  pull  up  a 
pumpkin  vine  or  an  untrellised  tomato  plant  late  in 
summer,  we  often  find  it  rooted  from  the  stem  at  some 
distance  from  the  original  root.     Lateral  roots  originate 


66  Principles  of  Plant  Culture. 

in  the  internal  tissues  of  the  stem  or  root  and  not  close 
to  the  surface,  as  do  buds  (131). 

88.  Moisture  Excites  Root  Growth.    .Roots  develop, 
as  a  rule,  from  portions  of  the  stem  that  are  maintained 
for  a  certain  time  in  contact  with  abundant  moisture. 
In  the  pumpkin  vine  and  tomato  plant  above  mentioned, 
nearness  to  the  soil  furnishes  a  moist  atmosphere.     A 
corn  stalk  pegged  down  to  the  ground  for  some  distance 
wiir usually  root  at  all  joints  of  the  stem  in  contact  with 
the  soil.     A  potato  plant  grown  under  a  bell-jar,  where 
the  air  is  nearly  saturated  with  water,  will  form  roots 
at  any  joint  of  the  stem.     In  parts  of  the  tropics  where 
the  air  is  very  moist,  certain  plants,  as  orchids  and  the 
Banyan  tree,*  emit  roots  freely  from  the  stem  above 
ground.     Cuttings   (358)    and  layers   (349)    form  roots 
because  they  are  maintained  in  contact  with  abundant 
moisture  and  at  a  suitable  temperature.     Cuttings  of 
some    plants,    as    the    willow    and    nasturtium,f    root 
promptly  when  their  stems  are  immersed  in  water. 

89.  Oxygen  is  Necessary  to  the  Life  of  Roots.  Since 
the  cells  of  newly-formed  roots  are  filled  with  proto- 
plasm, they  must  have  access  to  the  oxygen  of  the  air, 
or  they  can  neither  live  nor  grow.     This  is  shown  by  a 
simple   experiment.     Boil   a  quantity   of  water  fifteen 
minutes  or  longer,  to  exhaust  it  of  free  oxygen,  and  then 
cool  it  quickly  by  setting  the  dish  containing  it  in  cold 
water.     Now   place   a  healthy   cutting    (358)    of   some 
plant  that  roots  freely  in  water,  as  willow,  nasturtium 
or  wandering  jew,J  in  each  of  two  tumblers.     Pour  a 

*Ficus  Indica.       t  Tropoeolum.       I  Tradescantia. 


The  Root  and  the  Soil. 


67 


part  of  the  cool,  boiled  water  into  one  of  the  tumblers 
and  add  a  little  olive  oil  to  form  a  film  over  the  liquid 
thus  preventing  it  from  absorbing  more  air.  Then  agi- 
tate the  rest  of  the  water  vigorously  to  impregnate  it 
again  with  oxygen,  and  pour  some  of  this  into  the  sec- 
ond tumbler.  Set  both  tumblers  in  a  light,  warm  place. 
In  a  few  days  roots  will  start  freely  from  the  slip  in 

the  tumbler  in  which 
the  water  has  access 
to  the  air,  but  not  in 
the  other  (Fig.  27). 
If  now  the  rooted 
cutting  is  placed  in 
oil-covered  water  that 
has  been  exhausted 
of  its  oxygen  by 
boiling,  the  roots  will 
soon  die. 

The  copious  for- 
mation of  root-hairs 
(100)  that  reach  out 
into  the  moist  atmos- 
phere of  the  seed- 

FIG.   27.   Slips  of  Tradescantia  in  water 

containing    oxygen    (left    glass)    and    in  tester    (38),  and   that 
water  containing   no   oxygen  (right  glass). 
From    nature.  so    often   fills    the    Soil 

cavities  with  a  delicate,  cottony  down,  is  further  proof 
that  roots  search  for  air  as  well  as  water.  The  total 
absence  of  live  rootlets  in  the  puddled  clods  of  badly- 
tilled  fields  shows  that  roots  will  not  penetrate  soil  from 
which  the  air  has  been  expelled  by  undue  compression 
while  wet.  Plants  in  over-watered  greenhouse  pots 


68  Principles  of  Plant  Culture. 

sometimes  send  rootlets  into  the  air  above  the  soil  to 
secure  the  oxygen  from  which  their  roots  have  been 
deprived. 

90.  The    Ideal   Soil  for  Land   Plants   must  contain 
enough  plant"  food  and  water  to  fully  supply  the  plants, 
and  yet  be  so  porous  that  air  can  circulate  through  it 
and  come  in  contact  with  the  roots.     Each  particle  of 
such  a  soil  is  surrounded  by  a  thin  film  of  water,  while 
between  the  particles  are  spaces  connected  with  each 
other,  and  filled  with  moist  air  that  is  in  communica- 
tion with  the  air  above  the  soil.     The  root-hairs  (100) 
apply  themselves  intimately  to  the- wet  surfaces  of  the 
soil  particles,  or  reach  out  into  cavities  filled  with  sat- 
urated air,  and  are  thus  able  to  draw  in  the  well-aerated 
soil  water,  with  its  dissolved  food  constituents,  in  suf- 
ficient quantity  to  restore  the  loss  from  transpiration 
(74)  and  to  distend  the  newly  formed  cells  (62). 

91.  The  Soil  is  a  Scene  of  Constant  Changes.     The 
part  of  the  soil  in  which  the  roots  of  plants  grow  is  the 
field  of  most  potent  vital  and  chemical  activities.     The 
dead  remains  of  plants  and  animals  it  chances  to  con- 
tain  are  undergoing   decomposition   during  the   warm 
season,  by  serving  as  the  feeding  ground  of  myriads 
of  microscopic  plants  (bacteria)    (255).     Through  their 
agency  nitric   acid,  which   supplies  the   higher  plants 
with  their  most  valuable  food  element — nitrogen  (254), 
is  formed  in  the  soil.     The  carbonic  acid  these  remains 
took  from  the  air  during  growth  is   also  set  free  to 
slowly  disintegrate  the  mineral  soil  constituents,  ren- 
dering these  soluble  and  thus  available  as  plant  food. 
In  winter,  the  frost  separates  the  compacted  particles 


The  Root  and  the  Soil.  69 

of  clods,  making  the  latter  permeable  to  air  and  root- 
lets, or  flakes  off  new  fragments  of  rock,  thus  unlock- 
ing new  supplies  of  mineral  fertility. 

92.  The  Importance  of  Organic  Matter  in  the  Soil. 
Crops  secure  a  large  part  of  their  nitrogen,  as  w'ell  as 
of  other   food  substances,  from   dead  organic   matter, 
i.  e.,  animal  or  vegetable  materials.     The  application 
of  such  matter  to  the  soil  is,  therefore,  of  great  im- 
portance, where  large  crops  are  expected.     Stable  and 
barn-yard  manure,  the  offal  from  slaughter-houses,  tan- 
neries, breweries,  etc.,  are  all  valuable  for  this  purpose, 
when  wisely  used.     Stable  manure  is  further  beneficial 
by  absorbing  moisture,  oxygen,  ammonia  and  carbonic 
acid  from  the  air  as  well  as  much  solar  heat.     Not  only 
does  organic  matter  in  the  soil  furnish  plant  food,  but 
while  in  a  partially  decomposed  state  (humus),  it  ren- 
ders the  soil  porous   and  greatly  increases   its  water- 
holding  power. 

93.  The  Soil  Needs  Ventilation.     The  roots  of  grow- 
ing plants  and  the  decomposition  of  organic  matter  in 
the  soil  tend  constantly  to  exhaust  the  latter  of  its  free 
oxygen,  and  to  replace  this  with  carbonic  acid,  which 
is  not  used  by  the  roots.     Hence,  without  some  inter- 
change between  the  contents  of  the  soil  cavities  and  the 
atmosphere   above,    the   roots   sooner  or   later  become 
smothered    and    perish.      In    sufficiently    porous    soil, 
changes   in  temperature  and  in  atmospheric   pressure, 
aided  by  wind  and  rain,  furnish  the  needed  soil  ventila- 
tion, but  in  poorly-drained  soils,   and  soils  not  thor- 
oughly tilled,  the  roots  of  plants  often  suffer  from  in- 
sufficient oxygen.     A  puddled  crust  on  the  surface  of 


70  Principles  of  Plant  Culture. 

clayey  soil,  due  to  the  compacting  influence  of  rain,  is  a 
great  hindrance  to  its  ventilation.  Earthworms  and  other 
animals  that  burrow  in  the  soil  aid  in  aerating  it. 

94.  Hotbeds  Require  Especial  Care  in  Ventilation 
(365),  since  they  usually  contain  large  quantities  of  de- 
composing organic  matter  (manure),  which  rapidly  ab- 
sorbs oxygen  from  the  soil,  replacing  it  with  carbonic 
acid. 

95.  Drainage    Promotes   Soil    Aeration  by   forming 
an  outlet  for  the  surplus  water  that  would  otherwise 
fill  the  cavities.     Although  moisture  is  essential  to  root 
growth,  land  plants  do  not  prosper  with  their  roots  im- 
mersed in  water.     True,  most  plants  may  be  grown  in 
"water  culture,"  i.  e.,  with  their  roots  from  germina- 
tion grown  in  water  that  is  freely  exposed  to  the  air; 
but  the  roots  of  land  plants  soon  smother  for  want  of 
free  oxygen  when  the  soil  cavities  are  filled  with  water, 
because  the  soil  tends  to  prevent  the  water  within  its 
cavities  from  absorbing  air. 

96.  Potted  Plants  Require  Drainage  (412),  and  the 
outside  of  the  pots  should  be  kept  clean,  to  admit  air 
through  their  walls.     Potting  soil  should  contain  suffi- 
cient sand  and  humus  (92),  so  that  it  does  not  readily 
become  puddled  by  watering  (31). 

97.  Potted    Plants    should  be   Watered    with    Care 
(218).     They  should  receive  sufficient  water  so  that  the 
soil  particles  are  constantly  surrounded  with  a  film  of 
water,  but  not  so  much  that  the  soil   cavities  remain 
filled.    fa. 

98.  How  the  Root-Tip  Penetrates  the  Soil.    Darwin 
made  the  interesting  discovery  that  the  root-tip,  in  ad- 


The  Root  and  the  Soil. 


71 


vancing  through  the  soil,  does  not  move  in  a  straight 
line,  but  has  an  oscillating  motion,  which  enables  it  to 
take  advantage  of  openings  between  the  soil  particles. 
The  force  with  which  the  root-tip  is  pushed  forward  was 
calculated  by  Darwin  to  be  at  least  a  quarter  of  a  pound 
in  some  cases,  while  the  increase  of  the  root  in  diameter 
may  exert  a  much  greater  force.  The  root-tip  is  pro- 
tected in  its  passage  through  the 
soil  by  a  thimble-like  covering 
called  the  root-cap* 

99.  Growth  of  Roots  in  Length. 
Since  the  soil  offers  more  or  less 
resistance  to  the  growth  of  roots,  it 
is  evident  that  the  roots  of  land 
plants  cannot  elongate  through  their 
whole  length  at  once.  On  the  con- 
trary, the  part  that  increases  in 
length  is  limited  to  a  short  portion 
just  behind  the  root-tip.  Sachs 
found  that  the  part  of  the  rootlet 
of  the  broad  bean  that  increased  in 
length  by  growth  scarcely  exceeded 
FIG.  28.  Roots  of  young  half  an  inch  long.  In  Fig.  28,  the 

wheat  plant.     The  parts  ,  .  ,  , 

inclosed  in  sand  (R  H)  parts  that  are  increasing  in  length 

are       surrounded       by  . 

root-hairs.    R  T,  root-  are    considerably    shorter   than   the 

tips;    e,    older   parts    of 

root.      One-fourth    nat-  root-tips    (RT). 

ural   size.    (After  Frank 

and  Tschirch.)  IOO.  The    Root-Hairs  (Fig.  29  B) 

develop  just  behind  the  elongating  part  of  the  rootlet 
and  are  present  in  nearly  all  plants.     Their  object  is  to 


*  The  root-cap  is  readily  seen  without  a  magnifying  glass  when 
bean  plant  is  grown   in   water. 


72  Principles  of  Plant  Culture. 

absorb  water,  with  the  food  materials  it  contains.  The 
root-hairs  greatly  increase  the  absorbing  surface  of  the 
roots,  just  as  leaves  increase  the  absorbing 
"^  VN  surface  of  the  plant  above  ground.  Each 
root-hair  consists  of  a  single  elongated 
cell  (Fig.  30),  and  is  filled  with  proto- 
plasm, as  are  the  cells  in  other  living 
I  jjjjjjl  parts  of  the  plant  (13).  As  the  extrem- 
ity of  the  root  advances  through  the  soil 
by  growth,  new  root-hairs  are  formed  in 
front  of  the  older  ones,  while  those  far- 
thest back  as  rapidly  die  off,  so  that  only 
a  short  portion  of  a  rootlet  bears  root- 
hairs  at  any  one  time.  In  Fig.  27  root- 
hairs  are  visible  in  the  left  glass,  and  in 

FIG.  29.    Seed- 
lings of  turnip  Fig.  6  they  may  be  seen  on  the  hpyocotyl 

showing      root- 

hairs.      (After  of  some  of  the  germinating  corn  grains. 

.Frank     and 

Tschirch.)  in  Fig.  29  A  and  in  Fig.*  28  the  parts  of 
the  root  bearing  root-hairs  are  indicated  by  the  sand 
which  adheres  to  these  parts.  It  is  usually  difficult  to 
see  the  root-hairs  of  plants  growing  in  the  natural  soil, 


PIG.    30.     Magnified    root-hair    of    wheat,    in    contact    with    soil 
particles.     (After   Sachs.) 

but  they  may  sometimes  be  discovered  with  the  help  of 
a  pocket  magnifying  glass  by  carefully  removing  the 
soil  particles  about  the  younger  roots,  when  the  silky 
network  of  root-hairs  may  be  seen  filling  the  smaller 


The  Root  and  the  Soil.  73 

pores  of  the  soil  or  enveloping  the  soil  particles.  Fig. 
30  shows  a  magnified  root-hair  of  the  wheat  plant, 
closely  attached  to  some  particles  of  soil.  The  root- 
hairs  are  able  to  take  up  water  freely,  even  from  soil 
that  does  not  appear  very  wet,  because  each  soil  par- 
ticle is  enveloped  in  a  thin  layer  of  water  (90).  Still 
more  interesting  is  the  fact,  that  root-hairs  are  able  to 
dissolve  mineral  matters  in  the  soil,  by  their  excretions, 
most  important  of  which  is  carbonic  acid,  thus  permit- 
ting the  plant  to  use  these  matters  as  food. 

101.  Root-Hairs  Absorb  Water  with  considerable 
force.  It  is  the  absorptive  power  of  the  root-hairs  that 
causes  water  (sap)  to  flow  so  freely  from  injured  stems 
of  grape  vines*  and  some  other  plants  in  spring,  and 
from  wounds  in  the  trunks  of  some  trees  in  summer. 
This  force  is  probably  due  to  the  absorptive  power  of 
the  protoplasm  in  the  very  active  young  root  cells.  It 
is  affected  by  the  temperature  of  the  soil  within  cer- 
tain limits,  lessening  as  the  temperature  falls,  and  in- 
creasing as  it  rises.  Sachs  found  that  the  foliage  of 
plants  of  tobacco  and  pumpkin  drooped  when  the  tem- 
perature of  the  soil  in  which  they  were  growing  was  re- 
duced much  below  55°  F.,  showing  that  the  roots  did 
not  absorb  enough  water  at  that  temperature  to  com- 
pensate for  the  loss  by  transpiration  (74).  When  the 
soil  is  warm,  on  the  other  hand,  the  absorptive  power 
of  roots  may  be  sufficient  to  force  water  from  the  tips 
of  leaves  during  cool  nights  when  transpiration  is 
slight  (62). 

*  Hales  found  the  absorbing  force  of  the  roots  of  a  grape  vine 
equal  to  the  weight  of  a  column  of  mercury  thirty-two  and  one- 
half  inches   high. 
6 


74  Principles  of  Plant  Culture. 

102.  Only  the  Youngest  Parts  of  Roots  are  Active 
in   Absorption.     The   part   from   which  the   root-hairs 
have  perished  absorbs  little  water,  but  is  chiefly  useful 
in  giving  strength  to  the  plant  and  in  conducting  the 
plant  fluids.     The  absorbing  part  of  any  given  rootlet 
is,  therefore,  comparatively  short.     It  follows  that  the 
amount  of  nourishment  a  given  plant  can  receive  will 
depend  upon  the  number  of  its  root-tips.     Our  treat- 
ment of  the  plant  should,  therefore,  be  aimed  at  pro- 
moting the  formation  of  root-tips.     In  other  words,  we 
should   encourage   root   branching.*     How   can  we   do 
this? 

103.  The  Branching  of  Roots  in  land  plants  appears 
to  depend  much  upon  the  amount  of  free  oxygen  (31) 

and  available  plant  food  which 
the  soil  contains,  so  long  as  the 
moisture  supply  is  sufficient. 
In  cultivated  ground  having  a 
compact  sub-soil  the  roots  of 
annual  crops  usually  branch 
most  freely  just  at  the  bottom 
of,  or  a  little  below,  the  layer 
of  soil  stirred  by  the  plow,  this 
being  the  point  at  which  the 
FIG.  si.  showing  how  supply  of  oxygen,  plant  food 

root      pruning       stimuates  -,  •   ,  ,     i  i      T_ 

root  branching.  and  moisture  are  probably  best 

suited  to  root  growth.     As  the  depth  of  tillage  is  in- 
creased, roots  branch  freely  at  a  greater  depth.     Masses 

*  Root  branches  must  not  be  confounded  with  root-hairs.  In 
*ig.  28,  branches  of  the  roots  appear  at  e,  e,  e.  The  branches 
bear  root-hairs  when  of  sufficient  length,  but  root-hairs  never 
develop  into  branches. 


The  Root  and  the  Soil.  75 

of  decomposed  manure  beneath  the  surface  of  the  soil 
are  usually  penetrated  through  and  through  with  finely- 
branched  roots;  and  fragments  of  bone  in  the  soil  are 
often  inclosed  in  a  mat  of  delicate  rootlets.  These  ma- 
terials furnish  plant  food  in  abundance.  Roots  that 
penetrate  the  deeper  and  more  compact  layers  of  soil, 
on  the  other  hand,  and  those  in  poor  and  dry  soils,  are 
usually  little  branched.  It  is  clear,  therefore,  that  un- 
less a  soil  is  well  aerated  (93)  by  a  proper  system  of 
tillage,  and  by  draining  if  need  be,  and  unless  it  con- 


FIG.  32.  Showing  effects  of  transplanting  on  root  growth  of 
celery  plants.  The  left  two  plants  were  transplanted  when  quite 
small;  the  right  two  were  not.  (After  Green.) 

tains  abundant  soluble  plant  food  in  the  aerated  part, 
the  roots  of  plants  growing  upon  it  will  not  branch 
freely  and  hence  the  plants  cannot  be  well  nourished.^ 
104.  Transplanting  (400)  and  Root  Pruning  (416) 
Stimulate  Root  Branching.  Removing  the  growing 
points  of  either  the  stem  or  raot  (65)  stimulates  the 


76  Principles  of  Plant  Culture. 

development  of  other  growing  points  farther  back. 
Transplanting  or  root  pruning  accomplishes  this  in  the 
case  of  roots  (Fig.  31).  While  these  operations 
may  not  often  increase  the  total  number  of  root-tips, 
and  hence  may  not  enable  the  plant  to  take  up  a  greater 
amount  of  nourishment,  they  do  cause  the  development 
of  a  more  compact  root  system,  which  is  of  great  ad- 
vantage to  young  plants  grown  in  the  seed-bed  or  nur- 
sery for  subsequent  transplanting.  «jfc ^ 

105.  Pricking  Off   Young  Seedlings,  i.  e.,  transplant- 
ing them  from  the  soil  in  which  they  grew  to  other  soil, 
where  they  have  more  room,  is  an  important  prepara- 
tion for  their  final  transplanting.     They  should  receive 
as  good  care  after  pricking  off  as  before,  with  which 
they  soon  develop  many  new  rootlets  near  the  base  of 
the  stem,  that  need  be  little  injured  in  the  later  re- 
moval (Fig.  32). 

106.  Nursery  Trees  are  Benefited  by  Transplanting 
them  once  or  twice  before  the  final  planting  out,  for 
the  reasons  named  above. 

107.  Root  Pruning  (416  k)  is  sometimes  employed  as 
a  substitute  for  transplanting,  and  is  especially  useful 
to  trees  that  form  new  branch  roots,  as  the  hickory  and 
walnut.     In  this  case,   the  tap  root  is  cut  off  a  few 
inches  below  the  surface   of  the  soil  the  year  before 
transplanting.     -/— 

108.  The    Horizontal    Extent    of    Roots    is   usually 
greater  than  is  generally  supposed.     In  upright-grow- 
ing plants,  the  area  occupied  by  the  roots,  as  a  rule, 
exceeds  that  covered  by  the  foliage,  while  in  spreading 
and  trailing  plants,  the  roots  are  probably  not  often 


The  Root  and  the  Soil.  77 

less  in  extent  than  the  branches.  It  appears  from  the 
observations  recorded  that  even  in  such  plants  as  the 
melon  and  squash,  the  horizontal  extent  of  the  roots 
usually  equals  or  exceeds  that  of  the  runners.  As  the 
diffusion  of  soluble  matters  in  the  soil  water  is  probably 
much  hindered  by  the  soil  particles,  the  roots  of  plants 
need  to  travel  farther  after  food  than  do  the  branches, 
which  develop  in  a  freely  circulating  medium.  Espe- 
cially is  this  true  of  plants  growing  in  poor  soil,-/,. 

109.  The  Depth  of  Roots  in  the  Soil.  It  appears 
from  the  observations  recorded  that  the  extreme  depth 
reached  by  roots  is  generally  less  than  their  greatest 
horizontal  extent.  The  distance  reached  by  the  deeper 
roots  is  probably  governed  largely  by  the  nature  of  the 
sub-soil  and  the  depth  of  free  ground  water.  But  in 
most  annual  crops  a  comparatively  small  part  of  the 
root  system  develops  below  the  plow  line.  At  the 
Geneva  Experiment  Station*  the  chief  root-feeding 
ground  of  the  field  and  garden  crops  grown  in  that 
locality  appeared  to  be  from  three  to  ten  inches  below 
the  surface,  while  that  of  crops  making  large  develop- 
ment of  stem  and  foliage  during  summer,  as  Indian 
corn,  sorghum,  tobacco  and  the  Cucurbits,  appeared  to 
be  shallower  than  in  slower-growing  crops. 

A  portion  of  the  roots  of  many  crops  grow  very  near 
the  surface  of  the  ground.  Branches  from  the  main 
horizontal  roots  often  grow  upward  as  well  as  in  other 
directions.  At  the  Geneva  Experiment  Station,  numer- 
ous roots  of  sweet  corn  were  found  within  an  inch  of 


*  See    Report    of    New    York    Agricultural    Experiment    Station, 
1886,    p.   165. 


78 


Principles  of  Plant  Culture. 


the  surface,  and  in  a  tall-growing  southern  corn,  roots 
of  considerable  size  started  at  a  depth  of  only  half  an 
inch.  The  main  root  of  a  Hubbard  squash  vine  was 
traced  a  distance  of  ten  feet,  in  which  its  depth  varied 
from  two  to  five  inches.  In  tobacco  fields,  the  rootlets 
sometimes  literally  protrude  from  the  surface  of  the  soil 
in  warm,  wet  weather  (231). 

no.  The  Rate  of  Root  Growth  in  rapidly  develop- 
ing plants  is  often  extremely  fast.  President  Clark, 
formerly  of  the  Massachusetts  Agricultural  College, 
concluded  from  very  careful  examinations  and  measure- 
ments of  the  roots  of  a 
squash  vine  grown  un- 
der glass,  that  rootlets 
must  have  been  pro- 
duced at  the  rate  of  at 
least  one  thousand  feet 
per  day  during  the  lat- 
ter part  of  the  growth 
period.  \£. 

in.  Relation  of 
Roots  to  Food  Supply. 
In  the  extent  of  ground 
occupied,  root  growth  is 
relatively  less  in  moist 
and  fertile  soils  than  in 
poorer  and  drier  ones, 

FIG.  33.     Young  clover  plant  show-  but    the    roots    are    pro- 

nastureurc  ;From  p  or  t  i  on  a  t  e  1  y   more 

branched.  In  wet  seasons,  a  given  plant  has  less  ex- 
tensive root  development  than  in  drier  seasons,  because 


The  Stem. 


79 


the  roots  may  then  secure  the  needed  food  and  water 
from  a  smaller  area.  Nursery  trees  grown  on  fertile 
soils  have  a  more  compact  root  system  than  those  grown 
on  poorer  soils. 

112.  Root  Tubercles.  Plants  belonging  to  the  nat- 
ural order  Leguminosae  (le-gu-mi-no'-see),  of  which  the 
clover,  pea  and  bean  are  familiar  examples,  when  grown 
in  ordinary  soil  have  swellings  or  tubercles  on  their 
roots  (Fig.  33).  These  are  caused  by  micro-organisms, 
probably  of  the  class  known  as  bacteria,  and  are  of  spe- 
cial interest,  because 
the  organisms  pro- 
ducing them  render 
nitrogen  of  the  air 
available  as  plant 
food.  Plants  have  no 
power  to  utilize  di- 
reetly  the  free  nitro- 
gen of  the  air  (259). 
SECTION  VII.  THE 

STEM. 

113.  As  the  root 
develops  from  the 
base  of  the  hypo- 
cotyl,  the  plumule, 

FIG.    34.     Potato    plant.     U.    st.,    under-  or       primary       shoot 
ground  stems;   R,    roots.     The  tubers   are 

the  thickened  distal*  ends  of  the  under- (55),  develops  from 
ground  stems.  Much  reduced.  (After 

Frank  and  Tschirch.)  the    other    end    and 

becomes,  at  least  for  a  time,  the  main  axis  or  stem  of 
the  plant. 

*  See  foot  note  on  page  80. 


80 


Principles  of  Plant  Culture. 


114.  The  Stem  is,  generally  speaking,  the  part  of  the 
plant  that  supports  the  leaves.  In  exceptional  cases, 
as  in  the  potato  (Fig.  34)  and  quack  grass,  a  part  of 
the  stem  grows  beneath  the  ground,  on  which  the  leaves 
usually  do  not  develop  (underground  stems}]  and  in  a 
few  plants,  as  in  some  cacti,  the  stem  performs  the 
whole  office  of  leaves.  The  stem  may  be  strong  enough 
to  support  its  own  weight,  as  in 
trees  and  shrubs,  or  it  may  de- 
\  pend  upon  other  objects  for  its 

support,  as  in  vines. 

115.  Nodes  and  Internodes. 
Unlike  the  root,  the  stem  is  de- 
veloped in  successive  sections, 
comparable  in  part  to  the  stor- 
^  ies  of  a  building.  Each  section 
or  story  consists  of  one  or  more 
leaves,  attached  to  the  distal* 
end  of  a  portion  of  the  stem. 
The  part  of  the  stem  to  which 
the  leaf  or  leaves  are  attached  is 
called  a  node  and  the  part  be- 
low the  node,  or  in  the  stem  as 
of  the  box  eider,  Negun-  a  whole,  the  part  between  the 

do    aceroides;    B,     of    the         n          .          „    ,  .    . 

wild  grape,  vitis  riparia.  nodes,  is  called  an  tnternode. 

The  nodes  are  distinctly  marked  in  the  younger  stems 
of  most  plants  by  a  slight  enlargement  or  by  leaf -scars, 
if  the  leaves  have  fallen  (Fig.  35).  The  nodes  are 
centers  of  vital  activity  and  are  points  at  which  lateral 


*  Distal  means  farthest  from  the  point  at  which  growth  started. 
It  is  opposed  to  proximal,  which  means  nearest  the  point  of  origin. 


The  Stem.  81 

growing  points  (buds  127))  are  normally  formed,  and 
whence  roots  usually  start  first  in  cuttings  and  layers 
(358,  349). 

116.  The  Stem  Lengthens  by  Elongation  of  the 
Internodes,  as  well  as  by  the  formation  of  new  ones. 
As  the  internodes  soon  attain  their  ultimate  length,  it 
follows  that  the  stem  lengthens  only  near  its  distal  end. 
An  internode  that  has  once  ceased  elongating  does  not 
usually  resume  it,  hence  the  internodes  of  per- 
ennial plants  that  are  only  partly  elongated  at 
the  close  of  the  growing  season  in  general  re- 
main undeveloped.  When  growth  is  resumed 
in  spring,  the  formation  of  a  comparatively  long 
internode  beyond  the  very  short  ones  of  au- 
tumn usually  forms  a  perceptible  ring  about 
the  shoot,  which  enables  us  to  readily  locate  the 
\a  point  at  which  growth  started  in  the  spring 
(Fig.  36).  Indeed  we  caii  often  determine  the 
amount  of  growth  that  took  place  during  the 
preceding  season  or  even  farther  back. 
uS>Gn306f  II7'  The  Ultimate  Length  of  the  Inter- 
oidlr and  n°des  in  any  plant,  or  any  part  of  a  plant, 
wood.  depends  upon  the  rate  of  growth— rapid 
growth  producing  long  internodes,  and  vice  versa.  In 
the  same  species,  therefore,  the  average  length  of  the 
internodes  is  much  greater  in  vigorous,  young  plants 
than  in  old  ones;  in  the  main,  central  shoot  than  in 
the  branches,  and  when  growth  is  well  started  in  spring 
than  during  its  decline  in  autumn.  The  diameter  of 
young  internodes  that  are  not  unduly  shaded  is  gener- 
ally in  proportion  to  their  length,  hence  rapid'y-grow- 


82  Principles  of  Plant  Culture. 

ing  shoots  are  usually  thicker  than  slower-growing  ones. 
We  can  judge  of  the  comparative  vigor  of  nursery 
trees  by  observing  the  length  and  diameter  of  the 
internodes. 

118.  The  Stem   Elongates   Fastest  just  behind  the 
growing  point  (66),  and  at  least  in  young  plants,  just 
behind  the  primary  original  growing  point  (55).  When 
we  desire  to  check  the  growth  of  the  stem,  therefore,  we 
remove  the  terminal  growing  point  by  pinching  (416a). 

119.  Pinching    Stimulates    Branching    because    re- 
moving the  terminal  growing  point  stimulates  the  de- 
velopment of  other  growing  points  farther  back  (104). 

SECTION  VIII.     THE  LEAVES. 

We  have  seen  that  one  or  more  leaves  are  normally 
formed  at  each  node  of  the  stem  (115). 

120.  The   Function   of   Leaves   is   food  preparation 
(58).     Since   food  is  prepared  only  in  the  light,   the 
cells  of  leaves  are  in  most  plants  so   arranged   as  to 
best  expose  them  to  light,  i.   e.,  in  thin,  more  or  less 
horizontal   plates,   which  are  strengthened   and  at  the 
same  time  supplied  with  water  by  a  network  of  vascu- 
lar bundles   (67)   connecting  with  the  stem.     They  are 
protected  by  the  epidermis    (64),   but   have  access  to 
air  through  the  stomata  (65). 

Each  leaf,  like  the  stem  and  root,  is  developed  from 
one  or  more  growing  points  (66),  located  near  the  base. 
Cell  division  in  the  leaf  is  confined  to  the  near  vicinity 
of  the  growing  points,  hence  an  injury  to  the  older 
part  of  the  leaf  is  not  repaired  further  than  by  the 
formation  of  callus  (72)  over  the  wounded  parts. 


The  Leaves.  83 

121.  The    Cultivator    Should    Provide    for    Normal 
Leaf  Development.     Since  the  protoplasm  of  the  plant 
is  nourished  by  prepared  food    (58),    and  since  food 
preparation  in  most  plants  takes  place  almost  wholly 
in  the  leaves   (120),  it  is  of  first  importance  that  the 
plant  be  so  cared  for  as  to  promote  normal  leaf  devel- 
opment.    Without  this,  good  crops  are  impossible.     The 
plants  must  be  grown  far  enough  apart  so  as  not  to 
unduly  shade  each  other;  insects  and  fungi  must  not 
be  permitted  to  prey  upon  them  when  it  is  possible  to 
prevent  it;  and  the  leaves  must  not  be  needlessly  re- 
moved or  injured.     The  more  severe  the  climate,  the 
more  important  is  perfect  foliage,  because  more  reserve 
food  is  required  to  endure  a  long,  severe  winter  than 
a  short,  mild  one. 

122.  How    Far    Apart    Should    Plants   be    Grown? 
When  the  finest  developed  plants,  or  parts  of  plants, 
as  fruits,  flowers,  leaves,  stems  or  roots  is  desired,  the 
plants  should  not  be  grown  so  near  together  as  to  in- 
terfere with  each  other's  leaf  or  root  development.    But 
when  the  largest  crop   from  a  given  area  is  of  more 
importance   than    the    development    of    the   individual 
plant,   as   with  grain   crops,    the   loss    from  a  limited 
amount  of  shade  and  crowding  will  be  more  than  made 
up  by  the  increased  number  of  plants.     In  this  case, 
the  amount  of  crowding  that  will  give  the  maximum 
yield  will  depend  much  upon  the  fertility  and  moisture 
of  the  soil,  and  must  generally  be  determined  by  ex- 
periment. 

123.  Stem  and  Root   Development   Depend  on  the 
Number  of  Leaves.  Since  the  vascular  bundles,  through 


84  Principles  of  Plant  Culture. 

the  formation  of  which  the  stem  and  root  increase  in 
diameter,  originate  in  the  leaves  (67),  the  size  and 
firmness  of  the  stem  and  the  root  depend  somewhat 
upon  the  number  of  leaves  the  plant  bears.  The  more 
leaves  it  has,  the  more  solar  energy  it  can  transform 
into  plant  tissue.  The  stem  is  larger  beneath  a  vigor- 
ous leafy  branch,  and  if  cut  off  some  distance  above 
a  branch,  the  part  thus  deprived  of  its  foliage  ceases 
to  grow,  unless  it  develops  new  leaves.  Trees  growing 
in  the  dense  forest,  where  their  lower  branches  con- 
tinually perish  through  lack  of  light,  have  tall,  but 
very  slender  trunks,  and  their  wood  is  soft  because  it 
contains  comparatively  little  fibrous  tissue,  while  other 
trees  of  the  same  species  in  the  full  light  of  the  open 
field,  through  the  large  amount  of  solar  energy  ab- 
sorbed by  an  immense  number  of  leaves,  develop  mass- 
ive trunks,  of  which  the  wood,  being  packed  with 
fibrous  tissue,  is  much  stronger  than  that  of  the  forest 
tree. 

124.  The  Comparative  Size  of  Leaves  on  a  given 
plant  depends  much  on  the  water  supply  during  their 
formation.  The  leaves  of  sap-sprouts  (223),  that  take 
an  undue  proportion  of  water,  are  usually  very  large, 
and  in  upright-growing  plants,  the  leaves  on  the  more 
nearly  vertical  shoots  are  usually  larger  than  those  on 
the  horizontal  ones.  The  more  vigorous  the  plant,  the 
larger,  as  a  rule,  are  its  leaves,  and  the  softer  is  its 
woody  tissue. 

In  plants  grown  from  seed  to  secure  new  varieties, 
large  leaves  may  be  taken  as  evidence  of  superior  root 
development,  which  implies  capacity  to  endure  drought 


The  Leaves.  85 

and,  therefore,  hardiness.  In  the  apple,  the  large- 
leafed  varieties  are,  as  a  rule,  hardier  than  others,  prob- 
ably because  their  vigorous  roots  supply  the  needed 
water  during  the  dry  season,  thus  enabling  the  tree  to 
mature  healthy  wood  and  buds  which  can  pass  severe 
winters  unharmed  (174). 

Crops  grown  for  their  leaves,  as  cabbage,  lettuce,  to- 
bacco, etc.,  are  especially  liable  to  be  curtailed  by 
drought,  and  hence  should  be  given  the  culture  that 
best  promotes  soil  moisture,  as  abundant  surface  tillage 
and  liberal  manuring  (231). 

125.  Leaves    are  usually     Short-Lived  because  they 
become  clogged  with  those  mineral  matters  taken  up 
with  the  soil  water  which  are  not  used  by  the  plant 
(63)   and  which  do  not  pass  off  in  transpiration  (74). 
In  mcst  annual  plants   (337),  the  older  leaves  become 
useless  from  this  clogging  and  die  before  the  stem  is 
fully  developed,  and  in  most  perennials  the  leaves  en- 
dure but  a  single  season.     In  the  so-called  evergreen 
plants,  in  which  the  leaves  are  usually  very  thick  and 
are  often  well  protected  against  evaporation  by  a  very 
strongly  developed  cuticle  (64),  the  leaves  rarely  live 
more  than  a  few  years. 

126.  The  Manurial  Value  of  Leaves,  that  mature  on 
the  plant,  is  usually  small,  since  the  more  valuable  fer- 
tilizing materials  they  contain  pass  into  the  stem  before 
the  leaves  ripen  (170).     The  mineral  matters  contained 
in  largest  quantity  by  leaves  are  these  that  are  not 
used  by  the  plant,  but  have  been  deposited  with  them 
during  transpiration   (125). 


86  Principles  of  Plant  Culture. 

SECTION  IX.     THE  BUDS. 

127.  The  Buds.  Each  tip  of  the  stem  (66)  is  in 
most  plants  protected  with  a  covering  of  rudimentary 
leaves  or  leaf-scales,  and  the  tip  with  its  leafy  or  scaly 
covering  constitutes  a  bud.  A  bud  forming  the  apex 
of  a  shoot  is  called  a  terminal  bud;  one 
at  the  junction  of  a  leaf  with  the  stem 
(axil)  is  called  an  axillary  or  lateral  bud 
(Fig.  37). 

Each  bud  generally  includes  one  ter- 
minal and  several  axillary  growing  points. 
Aside  from  these,  which  in  the  stem  exist 
only  in  the  bud,  a  bud  is  simply  a  part  of 
the  stem  in  which  the  leaves  and  inter- 
nodes  are  in  the  embryo  stage. 
Buds.  I*1  most  perennial  plants,  the  rudimen- 
!'  tary  leaves  that  form  near  the  latter  end 
of  the  growing  season  are  changed  into  bud-scales,  which 
serve  to  protect  their  growing  points  from  excessive 
moisture  and  sudden  changes  in  temperature.  Axil- 
lary buds  which  have  not  yet  expanded,  are  clothed 
with  similar  scales.  Buds  inclosed  with  scales  are 
often  called  winter  buds.  To  more  effectually  shut  out 
water,  the  scales  are  coated  with  a  waxy  or  resinous 
layer  in  some  plants,  as  the  horse-chestnut  and  balm  of 
Gilead,  and  to  protect  them  from  too  sudden  changes 
of  temperature,  they  are  lined  in  other  plants,  as  the 
apple,  with  a  delicate  cottony  down.* 


*  A  vertical  section  of  the  onion  bulb  may  be  used  as  a  mag- 
nified illustration  of  a  bud  as  it  appears  in  winter,  and  that  of 
a  head  of  cabbage,  of  a  bud  unfolding  in  spring. 


The   Buds.  87 

128.  Lateral     Buds.     Nature     provides    very    early 
for  the  next  year's  growth  in  perennial  plants.     With 
the  expansion  of  each  leaf,  a  bud  begins  to  form  at 
its  axil,  destined  if  need  be  to  become  a  branch  at  a 
later    time.     Sometimes,    however,    especially    in    very 
vigorous  shoots,  the  embryo  buds  at  the  axils  of  the 
earliest  formed  leaves  remain  undeveloped. 

129.  Branches    Develop    from    Lateral     Leaf-Buds 
(131).     In  trees  and  shrubs    (woody  perennials),  the 
lateral  buds  do  not  usually  push  into  growth  until  the 
spring  after  their  formation,  unless  the  terminal  bud  is 
injured.     Indeed,   they  may   never   push   into   growth. 
Some  lateral    leaf-buds,    (131),    especially   those    most 
distant  from  the  terminal  bud,  usually  remain  dormant, 
through  want  of  light  or  nutriment,  and  are  overgrown 
by  the  enlarging  stem  the  following  year.     Such  over- 
grown buds,  stimulated  by  destruction  or  injury  of  the 
stem   above,   sometimes   push   into  growth   years  after 
their  formation. 

We  can  usually  decide  if  detached  dormant  shoots  of 
trees  and  shrubs,  as  cions  and  cuttings,  are  of  the  pre- 
ceding year's  growth  or  older,  since,  as  a  rule,  only 
wood  formed  the  preceding  year  has  visible  undevel- 
oped buds*.  A  bud,  in  pushing  into  growth,  consumes 
reserve  food  from  the  parent  branch.  The  more  hori- 
zontal a  branch  the  smaller  is  the  supply  of  water  to 
its  buds. 

130.  Adventitious   (ad-ven-ti'-tious)    Buds.  Although 
buds   are   normally   formed   only   at  the  nodes  of  the 

*  Exceptions  to  this  rule  are  not  uncommon  in  unthrifty  trees 
and  shrubs. 


88  Principles  of  Plant  Culture. 

stem,  they  may  under  the  stimulus  of  unusual  root  pres- 
sure (101)  be  formed  without  regard  to  nodes.  The 
trunk  of  a  vigorous  elm,  willow  or  horse-chestnut  tree, 
cut  off  early  in  the  season,  often  develops  a  multitude 
of  buds  from  the  thickened  cambium  (68)  at  the  top 
of  the  stump,  and  a  circle  of  shoots  often  spring  up 
about  the  base  of  a  tree  of  which  the  top  has  been  in- 
jured by  over-pruning  or  severe  cold.  Such  buds  are 
called  adventitious.  It  is,  however,  often  difficult  or 
impossible  to  distinguish  between  adventitious  buds  and 
those  that  have  been  previously  overgrown  (129). 

The  roots  of  many  plants,  as  the  plum,  choke  cherry, 
raspberry,  etc.,  develop  adventitious  buds  freely,  espe- 
cially when  injured,  a  fact  often  utilized  in  propaga- 
tion by  root  cuttings  (376). 

131.  Leaf-Buds  and   Flower-Buds.     Buds  may  con- 
tain only  rudimentary  leaves,  or  they  may  contain  rudi- 
mentary flowers,  with  or  without  leaves.     The  former 
are  called  leaf-  or  wood-buds,  the  latter  flower-  or  fruit- 
buds.  Flower-buds  are  modified  leaf-buds.  Both   origi- 
nate  in   the   cambium  layer    (68)    arid    are    normally 
located  at  the  apex  of  the  stem  or  in  the  axil  of  a 
leaf  (127-128). 

132.  Flower-Buds  are  often  Readily  Distinguished 
from  Leaf-Birds  by  location  and  appearance  the  same 
season  in  which  they  are  formed,  which  enables  the  fruit 
grower  to  anticipate  his  crop.     In  the  peach  and  apri- 
cot,  and   in  many  varieties   of  plum,   a  flower-bud  is 
normally  formed  on  each  side  of  the  leaf-bud  in  the 
young  shoots  of  bearing  trees   (Fig.  37).     In  the  apple 
and  pear,   the  flower-buds   are   less  definitely   located, 


The   Buds. 


89 


but  are  mostly  formed  on  the  short,  thick,  wrinkled  and 
crooked  branches  from  wood  three  or  more  years  old 
(fruit  spurs,  Figs.  42  and  43.)  In  some  fruits,  as  the 
apple,  cherry  and  peach,  the  flower-buds  are  usually 
thicker  and  more  rounded  than  the  leaf-buds,  especially 
toward  spring.  Close  and  persistent  observa- 
tion will  enable  the  horticulturist  to  early  dis- 
tinguish the  flower-buds  in  many 
of  his  perennial  plants. 


FIG. 


FIG.  40. 


FIG.  41. 


FIG.  42. 


FIG.  38.     Flower-buds    of    Pottawattamie    plum,    Prunus    angus- 
tifolia.     The  central  bud   of  each   group   is   a    leaf-bud. 

FIG.  39.     Fruiting  branch  of  European  plum,   Prunus   domestica. 
B,   young  wood.     A,  wood   of  preceding  year.     S,    fruit  spurs. 

FIG.  40.  Fruiting  branch  of  Morello  cherry,  Prunus  cerasus. 
B,  young  wood.  A,  wood  of  preceding  year.  F,  clusters  or  rruit 
buds. 

FIG.  41.     Leaf-buds    of  the   apple. 

FIG.  42.     Fruit-bud  of  apple  (F). 

All   are    reduced    one-half. 
Barry.) 


'(Figs.    39,    40,    41    and    42    are   after 


In  the  apple  and  pear,  the  buds  on  the  so-called  fruit- 
spurs  are  not  necessarily  flower-buds,  but  some  seasons 
all  are  leaf-buds.  How  early  in  the  life  of  a  bud  its 
character  is  fixed,  or  if  flower-buds  ever  change  to  leaf- 

7 


90  Principles  of  Plant  Culture. 

buds  before  expanding,  does  not  appear  to  be  known. 
The  facts  that  leafy  shoots  sometimes  grow  out  of  the 
center  of  flowers,  and  that  petals  (142)  are  sometimes 
developed  as  leaves,  suggest  that 
such  a  change  may  occur. 

In  the  grape,  flowers  appear  at 
a         the  first  two,  three  or  four  nodes 


FIG.    44.     Fruit   spur   of    the   pear. 
duced    one-half.     (After    Barry.) 


FIG.  43.  Fruit  spurs  of  of 

the    apple.     A,    points   at 


the    young    shoots    that    grow 

e    appe.        ,    pons   a     „  ,,  j  . 

which   apples  were   de-  from  stems  formed  the  preceding 

tached      the       preceding 

year;  w,  wrinkles  mark-  season   (canes)   and  tne  snoot  con- 

ing     points      at      which 

leaves   were   detached   in  tinues   to  grow  beyond   the   flowers. 

previous       years.         Re- 

duced. (After  Hardy.)  The  raspberry,  blackberry  and 
dewberry  blcom  like  the  grape,  except  that  the  shoots 
terminate  in  a  flower.  In  the  strawberry,  the  terminal 
bud  of  the  preceding  year's  growth  flowers  in  early 
spring.  In  these  plants,  therefore,  the  flower-buds  are 
enclosed  by  the  same  bud  scale  that  inclose  the  leaf- 
buds,  hence,  it  is  more  difficult  to  foresee  the  number 
of  flowers  than  in  the  tree  fruits.  A  knowledge  of  the 
location  of  the  flower-buds  is  very  important  in  pruning 
plants  grown  for  their  flowers  or  fruits  (416). 


The   Buds.  91 

133.  The  Comparative     Vigor    of    Leaf-Buds    on    a 

given  shoot  depends  somewhat  upon  their  location  and 
the  length  and  diameter  of  the  internodes.  The  ter- 
minal bud,  when  uninjured,  is  usually  the  most  vigor- 
ous one,  and  the  vigor  of  the  buds,  as  a  rule,  dimin- 
ishes as  we  recede  from  the  terminal  bud.  The  more 
rapid  the  growth  of  the  shoot,  the  less  developed,  as  a 
rule,  are  the  lateral  buds.  Cions  (386)  and  cuttings 
(358)  should  not,  therefore,  be  taken  from  excessively 
vigorous  shoots.  The  more  vigorous  buds  are  often  ten- 
derer to  endure  cold  than  the  less  vigorous  ones,  since 
they  are  usually  farther  developed  the  season  in  which 
they  are  formed,  hence  the  terminal  buds  are  most  often 
injured  in  winter. 

In  the  potato  tuber,  which  is  the  thickened  terminus 
of  an  underground  stem  (Fig.  34),  the  most  vigorous 
shoot  comes  from  the  terminal  bud  (the  so-called  seed- 
end)  ,  hence  rejecting  this  part  of  the  tuber  in  plant- 
ing, as  has  often  been  recommended,  is  detrimental  to 
the  crop. 

134.  Conditions  Affecting  the  Formation  of  Flower- 
Buds.     The   majority   of   cultivated   plants   are  grown 
either  for  their  flowers  or  the  product  of  their  flowers, 
i.  e.,  fruit  or  seed.     But  the  flower  is  not  an  essential 
part   of  the  plant,   and  instead  of  contributing  to  its 
welfare,   as  do  the  leaves   and  roots,   it  actually  con- 
sumes a  part  of  the  plant's  reserve  food    (139).     As 
might  be  expected,  therefore,  perennial  plants  do  not 
always  produce  an  annual  crop  of  flowers,  even  when 
well  developed  in  other  directions,  hence  the  grower  is 
often  disappointed.     Since  flowers  can  only  come  from 


92  Principles  of  Plant  Culture. 

flower-buds,  a  knowledge  of  the  laws  that  govern  the 
formation  of  these  would  often  be  valuable  to  the  cul- 
tivator. Unfortunately,  this  subject  has  received  less 
attention  than  is  due  to  it.  Two  principles  may  be 
cited,  however,  which  if  they  do  not  explain  all  phe- 
nomena connected  with  the  formation  of  flower-buds, 
are  of  sufficient  general  application  to  have  great  eco- 
nomic value,  viz. : 

A — Plants  form  flower-buds  only  when  they  contain 
reserve  food  (84). 

B — A  water  supply  insufficient  for  rapid  growth  may 
suffice  for  abundant  food  formation  (59). 

In  support  of  the  first  of  these  propositions,  we  men- 
tion :  (a)  Rapidly-growing  plants  rarely  form  many 
flower-buds  because  the  food  is  used  up  in  growth  as 
fast  as  formed,  (b)  Checking  such  rapid  growth,  by 
removing  the  growing  points  of  the  stem  or  root  (67), 
or  by  withholding  water,  results  in  an  accumulation  of 
food  and  is  often  followed  by  an  abundant  formation 
of  flower-buds,  (c)  Obstructing  the  rootward  current 
of  prepared  food  (79),  as  by  "ringing"  (416  g)  causes 
an  accumulation  of  food  above  the  obstruction  and  is 
often  followed  by  the  formation  of  flower-buds  in  that 
part. 

In  support  of  the  second  proposition  we  mention: 
(a)  Florists  often  bring  their  plants  into  bloom  at  a 
desired  time  by  withholding  water,  (b)  The  flower- 
buds  of  most  out-door  plants  are  formed  during  the 
drier  part  of  summer,*  when  a  restricted  water  supply 

*  Plants  that  live  over  winter  and  bloom  in  spring,  as  the 
apple,  strawberry,  etc.,  form  their  flower-buds  the  .  preceding 
season. 


The  Buds.  93 

prevents  rapid  growth,  but  when  abundant  sunlight 
and  fully-expanded  foliage  favor  food  formation  (59). 

We  may  infer,  therefore,  that  treatment  that  favors 
the  accumulation  of  reserve  food  promotes  the  forma- 
tion of  flower-buds,  a  proposition  that  is  borne  out  by 
the  experience  of  practical  cultivators. 

135.  How  can  we  Promote  the  Accumulation  of 
Reserve  Food  ?  Three  general  principles  may  be  cited : 

A — Provide  for  abundant  food  formation  by  giving 
sufficient  light  and  air  and  by  protecting  the  foliage 
from  attacks  of  insects  and  fungi  (Chap.  Ill,  Section 
VII). 

B — Provide  sufficient  plant  food  in  the  soil  to  satisfy 
all  requirements  of  food  formation  (Chap.  Ill,  Sec- 
tion VI). 

C — Provide  for  a  moderate  check  to  growth  after  the 
proper  amount  of  growth  has  been  secured. 

In  the  greenhouse  where  conditions  are  under  con- 
trol, these  principles  are  readily  followed,  and  the 
skilled  florist  rarely  fails  to  secure  bloom  at  the  proper 
time.  He  gives  the  desired  check  to  growth  by  permit- 
ting the  roots  to  become  densely  matted  in  the  pot  (pot- 
bound),  by  withholding  water,  or  by  pinching  the  tips 
of  the  more  vigorous  shoots.  With  out-door  perennial 
plants,  as  fruit  trees,  the  problem  is  more  difficult,  since 
conditions  are  less  under  control  than  with  plants  un- 
der glass,  but  the  principle  just  cited  should  always  be 
kept  in  mind  and  carried  out  so  far  as  possible. 

We  can  give  sufficient  light  and  air  by  planting  the 
trees  a  sufficient  distance  apart  (122)  and  by  proper 
pruning  (Chap.  IV,  Section  III). 


94  Principles  of  Plant  Culture. 

If  the  soil  is  properly  drained,  the  natural  depletion 
of  soil  water  about  midsummer  will  usually  give  the 
needed  check  to  growth.  In  wet  seasons,  the  drying  of 
the  soil  may  be  promoted  by  stopping  cultivation  before 
midsummer  and  sowing  a  crop  that  will  increase  evap- 
oration from  the  soil,  as  oats,  clover  or  buckwheat 
(200). 

136.  Pinching  Promotes  Flowering   (416).     In  cer- 
tain cases,   as  with  seedling  trees  of  which  we  would 
early  know  the  quality  of  the  fruit,  we  may  give  an  a-fr- 
normal  check  to   growth  by  pinching  the  tips  of  the 
young  shoots  or  by  root  pruning  (416  k).     These  opera- 
tions should  be  performed  early  in  summer,  before  the 
period  of  flower-bud  formation,  and  if  the  tree  is  not 
too  young,  flowers  and  fruit  may  be  expected  the  fol- 
lowing season.     Frequent  transplanting  of  young  trees 
acts  like  root  pruning,  especially  if  the  tap-root  is  sev- 
ered.    Such  harsh  measures,  however,  while  they  pro- 
mote early  fruiting,  doubtless  tend  to  shorten  the  life 
of  trees. 

137.  Ringing  (415  g)  often  Causes  the  Formation  of 
Flower-Buds  in  otherwise  barren  trees,  by  obstructing 
the   rootward   current   of   prepared   food.     Twisting   a 
small  wire    about    the    branch,  violently  twisting    the 
branch  itself,  or  simple  bending  and  fastening  it  in  an 
unnatural    position,    answers    the    same   purpose.     But 
these  devices  probably  weaken  the  tree  and  shorten  its 
life  by  robbing  the -roots  of  their  normal  food  supply 
and  are  excusable  only  in  special  cases,  as  with  seedling 
trees.     It  is  generally  a  reproach  to  the  care  or  knowl- 


The  Flower.  95 

edge  of  the  cultivator,  if  his  trees  of  bearing  age  cannot 
form  flower-buds  without  such  choking. 

Fruit  trees  grafted  on  slightly  uncongenial  stocks 
sometimes  flower  and  fruit  more  freely  for  a  time  than 
when  growing  on  their  own  roots,  because  the  imperfect 
union  of  cion  and  stock  (383)  forms  an  obstruction  to 
the  rootward  food-current. 

SECTION  X.     THE  FLOWER. 

138.  The    Flower   is  the   developed    and    expanded 
flower-bud   (131).     Its  office  is  to  provide  for  the  for- 
mation of  new  plants  of  its  kind  (reproduction,  (16)). 
Some  plants,  as  the  quack  grass,*  Canada  thistlef  and 
horseradish^  multiply  freely  in  nature  without  the  aid 
of  flowers,  and  nearly  all  plants  may  be  multiplied  in 
culture   by   other  means,    but   in   most   of   the    higher 
plants,  the  flower  is  the  natural  organ  of  reproduction, 
and  the  only  organ  devoted  solely  to  this  end. 

139.  Flowers  Tend  to  Exhaust  the  Plant,  since  they 
are  formed  from  the  food  prepared  by  the  leaves.     But 
since  flower-buds  are  not  usually  formed  until  the  needs 
of  growth  are  provided  for   (134 A),  the  normal  pro- 
duction of  flowers  does  not  injure  the  plant.     In  cer- 
tain cases,  however,  as  in  plants  weakened  by  recent 
transplanting  or  in  cuttings   (358),  flower-buds  should 
be  removed  as  soon  as  discovered,  to  prevent  their  ex- 
haustive influence. 

140.  The  Parts  of  the  Flower.     The  complete  flower 
is  composed  of  four  different  parts  or  organs.  A  knowl- 
edge of  these  parts  is  of  great  importance  to  the  botan- 

*  Agropyrum  repens.        f  Cnicus  arvensis.         |  Nasturtium  Armoracia. 


96  Principles  of  Plant  Culture. 

1st  in  determining  species,  and  also  to  the  plant  breeder 
who  would  practice  cross-pollination  (151,  440),  hence 
we  need  to  consider  them  in  detail.  The  cherry  blos- 
som, of  which  a  vertical  section  appears  in  Fig.  45,  will 
serve  as  our  first  example. 

141.  The  Calyx  (ca'-lyx).     Beginning  at  the  bottom, 
the  part  marked  C  in  the  figure  is  called  the  calyx.  This 
is  green  in  the  normal  cherry  flower.     In  some  plants, 
as  the  flax,  the  calyx  is  composed  of  several  distinct, 

more  or  less  leaf- 
like  parts,  each  of 
which  is  called  a 
sepal  (se'-pal).  In 
the  cherry  blos- 
som, the  sepals  are 
united  nearly  to 
the  top.  The  calyx 

PIG.   45.     Section   of   cherry  blossom.     C,     •  -,-, 

calyx;    Cor.,    corolla;    S,    stamens.  IS     Usually     green, 

but  in  the  tulip  and  some  other  flowers  it  is  of  another 
color.  In  the  apple  and  pear,  the  calyx  becomes  a 
part  of  the  fruit,  and  its  points  are  visible  in  the  de- 
pression opposite  the  stem. 

142.  The   Corolla    (co-ror-la).     The  more  spreading 
part  of  the  cherry  blossom,  which  is  normally  white 
(Cor.,  Fig.  45)   constitutes  the  corolla.     In  the  cherry, 
the  corolla  consists  of  five  distinct  parts,  only  three  of 
which  appear  in  the  figure,  called  petals  (pet'-als).     In 
many  plants,  as  the  pumpkin  and  morning  glory,  the 
petals  are  united.     In  other  plants  they  are  united  a 
part  of  the  way  to  the  top.     The  corolla  is  usually  of 
some  other  color  than  green. 


The  Flower.  97 

143.  The    Stamens    (sta'-mens).     Inside  the   corolla 
is   a  group   of  slender  organs    (S  S,  Fig.    45),   called 
stamens.     Each   stamen    consists    of    three   parts,    viz., 
the  long  and  slender  portion,  connected  with  the  calyx 
below,  called  the  filament  (fil'-a-ment)  ;  the  swollen  part 
at  the  top,  called  the  anther  (another)  ;  and  the  yellow 
dust  found  upon  or  within  the  anther,  called  the  pol- 
len   (pol'-len).     Each  grain  of  pollen  is  a  single  cell, 
which  if  fertile  (152)   contains  living  protoplasm.     The 
pollen  is  set  free  at  maturity. 

144.  The  Pistil    (pis'-til).     The  column-like  part  in 
the  center  of  the  flower  is  called  the  pistil.     This  also 
consists  of  three  principal  parts,  viz.,  the  enlarged  flat- 
tened summit,   called  the  stigma   (stig'-ma)  ;  the   egg- 
shaped  base,  called  the  ovary  (o'-va-ry)  ;  and  the  slen- 
der part  connecting  the  two,  the  style.     The  ovary  con- 
tains   a    smaller,    egg-shaped    part,   called    the    ovule 
(o'-vule),    which    when    developed    becomes    the    seed. 
Many  flowers  have  more  than  one  pistil,  and  many  ova- 
ries contain  more  than  one  ovule. 

Recapitulating,  the  parts  of  the  flower  are,  in  the 
order  we   have  considered  them: 

a— The   calyx;   when   divided,   the   parts   are  called 

sepals. 
b — The  corolla;  when  divided,  the  parts  are  called 


c — The  stamens;  the  parts  are  the  filament,  anther 

and  pollen. 
d — The   pistil   or  pistils;  the  parts  are  the  stigma, 

ovary  and  style. 
The  ovary  contains  the  ovule  or  ovules. 


98  Principles  of  Plant  Culture. 

145.  The  Parts  of  the  Flower  Vary  in  Form  in  dif- 
ferent species.     In  the  pea  flower   (Fig.  46)    the  five 

petals,    shown 
separately    in 
Fig.  47,  are  not 
quite    un- 
the   petals 

si 


only 

like 

of     the     cherry 

flower,    but,    as 

appears, 


FIG.  46.  FIG.  47. 

FIG.  46.   Flower  of   the  pea,    Pisum   sativum. 
(After    Baillon.) 

FIG.  47.     The  same   dissected,   showing  vari-  ri  i 

ation  in  form  of  the  petals.     (After  Figurier.)     are    unlike    each 

other.  The  stamens  (Fig.  48  st.)  and  the  pistil  (Fig. 
49)  of  the  pea  are  also  quite  different  in  form  from 
those  of  the  cherry.  The  variety  of  form  in  the  parts 
of  the  flowers  of  different 
species  is  almost  infinite. 

146.  Certain  Parts  of  the 
Flower  are  often  Wanting. 
The  flowers  of  the  maple 
have  no  corolla;  those  of  the 
willow  have  neither  calyx  nor 
corolla;  certain  flowers  oi 
the  pumpkin,  Indian  corn 
and  many  other  plants  have 
no  stamens,  while  other  flow- 


FIG.  48 


FIG. 

FIG.  48.      Stamens    (st)    and 
pistil   of   the   pea,    Pisum   sat- 

ers  of  the  same  species  have    ivum. 

FIG.  49.     Pistil   of    the   same 
no    pistils     (153).       In     many    alone.     (After    Baillon.) 

varieties  of  the   American   plums*   the   pistil  is  often 
wanting. 

147.  Composite    (com-pos'-ite)    Flowersf    are   made 

*Prunu»  Americana,  P.  angustifolia,  P.  horlulana. 
t  The  plants  having  composite  flowers  form  an  extensive  family 
in   botany,    called   Compositae. 


The  Flower. 


99 


of  several  individual  flowers  in  the  same  flower-head. 
The  sun-flower  (Fig.  50)  is  a  familiar  example  of  a 
composite  flower.  One  of  the  separate  flowers  is  shown 
in  Fig.  51.  At  the  outer  edge  of  the  flower-head,  is  a 
row  of  individual  flowers,  each  of  which  has  a  long, 

yellow,  petal-like 
appendage  (Fig. 
52),  called  a  ray. 
The  flowers  bear- 
ing rays  are  called 
ray-flowers.  Some 
composite  flowers 
as  of  the  tansy* 
are  without  ray- 
flowers. 

FIG.    50.     Cross-section   of   flower-head   of 

sunflower,     Helianthus     annuus.       Reduced.         148.    The     FiOW- 
The    florets    appear   closely   crowded    in    the 
center   of   the   head.  ers    of    the    Grass 

Familyf  to  which  the  cereals  belong,  as  well  as  corn, 
sorghum,  sugar  cane,  etc.,  are  quite  different  from 
those  of  most  other  plants.  In  this  family,  the  flowers 
are  arranged  in  little  groups, 
each  of  which  is  called  a 
spiJcelet.  What  we  call  a 
'head  of  wheat  is  made  up 
of  a  number  of  spikelets, 
one  of  which  is  shown  in 
Fig.  53.  Fig.  54  shows  the 
spikelet  dissected.  The  two 

scale-like   parts   at  the   base,    SUF?G.1;2r' Ray -flower  of  same, 
g.  g.,  are  called  glumes.    The  similar  pair  above,  tipped 

*  Tanacetum  vulgare.       f  Graminece. 


FIG.  52. 
Enlarged   floret   of 


100  Principles  of  Plant  Culture. 

with  a  bristle  (the  awn  or  beard)  are  called  the  lower 
or  outer  pales  or  palets  (pa'-lets)  or  flowering  glumes — 
to  distinguish  them  from  the  smaller  and  more  deli- 
cate upper  or  inner  palets  which  are  just  above  and 
inclosed  within  the  outer  palets.  Between  the  outer 


FIG.  53.  FIG.  54.  FIG.  55. 

FIG.  53.  Spikelet  of  wheat;  st,  stamens.  (After  LaMaout  and 
Dacaisne.) 

FIG.  54.  The  same  dissected;  x,  axis  of  spikelet;  g.  glumes; 
bl,  b2,  outer  pales;  Bl,  B2,  flowers  displaced  from  the  axis  of 
outer  pales;  ps,  inner  pales;  a,  anthers,  f  ovary.  (After  Prantl.) 

FIG.  55.  Flower  of  wheat,  enlarged;  st,  stamens;  p,  pistil;  o, 
ovary.  (After  LaMaout  and  Dacaisne.) 

and  inner  palets   are  the  stamens   and  pistils,  shown 
separately  in  Fig.  55. 

149.  Fecundation  (fec'-un-da'-tion)  is  the  union  of 
the  male  and  female  cell  by  which  the  new  plaritlet  is 
formed.*  The  ovule  produces  within  itself  a  female 
cell  which  may  be  fecundated  by  the  male  cell  pro- 
duced by  the  pollen  (143).  The  fecundated  cell  then 
grows  to  form  a  young  plant — the  embryo  (55),  and 
the  parts  of  the  ovule  develop  about  it,  the  whole  form- 
ing the  perfect  seed.  Unless  the  ovule  is  fecundated, 
the  seed  very  rarely  develops.  A  flower  that  contains 

*  The  term  fertilization  (fer-til-i-za'-tion),  that  has  been  com- 
monly used  for  this  process,  tends  to  confusion,  because  this  term 
is  also  applied  to  the  addition  of  plant  food  to  the  soil. 


The   Flower.  101 

no  pistil  and  hence  no  ovule,  can  of  course  produce  no 
seed. 

150.  Pollination  (pol-lin-a'-tion),  is  the  access  of 
pollen  (143),  to  the  stigma  (144)— the  first  step  in  the 
process  of  fecundation.  During  a  certain  period,  the 
surface  of  the  stigma  is  moistened  by  the  secretion  of  a 
viscid  liquid,  to  which  the  pollen  grains  readily  ad- 
here. Fertile  pollen  grains,*  alighting  on  the  stigma 
of  sufficiently  near-related  plants  during  this  period, 
undergo  a  process  comparable  to  germination,  in  which 
a  slender  projection  from  the  pollen  cell  penetrates 
the  stigma,  passes  lengthwise  through  the  center  of  the 
style  and  enters  the  ovule,  where  fecundation  occurs. 

Pollination  is  not  necessarily  followed  by  fecunda- 
tion. In  young  plants,  and  in  older  plants  that  are 
lacking  in  vigor  (9),  flowers  often  fail  to  produce  seed 
or  fruit,  even  when  pistil  and  stamens  appear  to  be 
normally  developed,  and  pollination  occurs.  Pollen  is 
probably  more  profuse  and  more  potent  some  seasons 
than  others. 

In  some  flowers,  as  in  the  pea,  the  stigma  is  brought 
into  direct  contact  with  the  pollen  by  the  elongation  of 
the  style,  but  in  most  plants  the  pol-en  must  be  trans- 
ferred to  the  stigma  by  some  outside  influence,  as  by  in- 
sects, the  wind,  or  gravity.  Most  flowers  which  have  a 
showy  corolla  or  calyx,  or  secret  nectar,  or  yield  a  fra- 
grant perfume,  depend  largely  upon  the  visits  of  pol- 
len-loving or  nectar-loving  insects  for  pollination.  The 
showy  parts  and  the  perfume  serve  as  signboards  to 
direct  the  wandering  insects  to  the  flowers.  Pollination 
is  favored  by  a  warm,  dry  atmosphere. 

*  Fertile  pollen  is  pollen  that  is  capable  of  fecundating  female 
cells  of  its  own  species. 


102  Principles  of  Plant  Culture. 

151.  Cross-Pollination    occurs  when   the   stigma   re- 
ceives pollen  from  a  different  plant,  especially  from  a 
plant  of  a  different  variety  or  species   (21).     The  fec- 
undation resulting  constitutes  a  cross  or  hybrid,  as  the 
case  may  be  (23).  Cross-pollination  is  often  performed 
artificially  (440). 

Close-  or  self-pollination  occurs  when  the  stigma  re- 
ceives pollen  form  its  own  flower  or  plant. 

152.  Cross-PoHination    is    Advantageous    in   plants, 
as   Darwin's    careful  experiments    have    shown.     The 
seeds  formed  are  usually  more  numerous  and  larger  and 
make  more  vigorous  plants  than  with  close-pollination. 
Especially  is  this  true   when  the  parent   plants   have 
been  subjected  to  different  growth  conditions  in  pre- 
vious  generations.     Nature    favors   cross-pollination   in 
perfect-flowered  plants  by  numerous  adaptations  tend- 
ing to  prevent  self-pollination,  as  maturing  the  pollen 
either  before  or  after  the  receptive  stage  of  the  stigma, 
or  so  locating  the  stamens  that  the  pollen  is  not  readily 
deposited  on  the  stigma  of  the  same  flower.*     In  some 
cases,  pollen  is  infertile  on  a  stigma  of  the  same  flower 
or  plant  that  is  abundantly  fertile  on  stigmas  of  other 
plants  of  the  same  species  (154). 

153.  Perfect,   Monoecious    (mo-nce'-cious)  and  Dioe- 
cious   (di-oa'cious)    Flowers.     Flowers  containing  both 
stamens  and  pistils  (or  pistil),  as  in  the  apple,  tomato, 
cabbage,  etc.,  are  called  perfect  or  hermaphrodite  (her- 
maph'-ro-dite)  ;  those  containing  but  one  of  these  or- 
gans, as  in  the  melon,  Indian,  corn,  etc.,  are  called  im- 

*  Darwin's  work  "On  the  Various  Contrivances  by  which  Or- 
chids are  Fertilized  by  Insects"  describes  many  most  interesting 
adaptations  of  this  sort. 


The  Flower.  103 

perfect  or  unisexual  (u'-ni-sex'-ual).*  Flowers  of  the 
latter  class  are  called  monoecious  when  the  stamen-bear- 
ing (staminate  (stam'-i-nate) )  and  pistil-bearing  (pis- 
tillate (pis'-til-late))  flowers  are  both  produced  on  the 
same  plant,  and  dioecious  when  produced  on  different 
plants  only,  as  in  the  hop  and  date.  In  a  few  plants', 
as  the  strawberry  (154)  and  asparagus,  some  individu- 
als produce  perfect,  and  some  imperfect  flowers. 

154.  Planting  with  Reference  to  Pollination  is  im- 
portant in  certain  plants.  All  direcious  plants  (153) 
intended  for  seed  or  fruit  must  have  staminate  and  pis- 
tillate plants  growing 
near  together  or  they 
will  not  be  productive. 
The  hop  plant,  persim- 
mon and  date  palm  are 
of  this  class. 

FiG5        Imperfect     flqw?r°' "'   the          The    fl°WerS    °f    manv 
StFaiG.b57.ry'Perfect     flower     of    same.    of   our     most    productive 

Jirc'uiaT  mlssu\tp\he1%eanptlrearar1ound  varieties  of  strawberry 
F£ch57.th(  seen  in  yield  little  or  no  pollen 

and  are  unproductive,  unless  growing  near  pollen-bear- 
ing sorts  (Figs.  56,  57).  In  many  varieties  of  Ameri- 
can plums  and  in  certain  varieties  of  the  pear  and 
apple,  the  pollen,  even  though  produced  freely,  is  in- 
fertile on  stigmas  of  the  same  variety.  To  insure  fec- 
undation, it  is  wise  to  mingle  varieties  in  fruit  planta- 
tions rather  than  to  plant  large  blocks  of  a  single 
variety. 

*  The     terms     hermaphrodite,    unisexual    and    bisexual,     though 
often  applied  to  flowers,  are  inaccurate. 


104  Principles  of  Plant  Culture. 

SECTION  XI.     THE  FRUIT  AND  THE  SEED. 

155.  The  Fruit,  as  the  term  is  used  in  botany,  is  the 
mature  ovary  with  its  contents  and  adherent  parts;  it 
may  be  hard  and  dry,  as  in  the  wheat  and  bean,  or  soft 
and  pulpy,  as  in  the  apple  and  melon.     But  in  common 
language  the  term  fruit  is  limited  to  the  pulpy  and 
juicy  part  of  certain  plants  that  contains  or  supports 
the  seed  or  seeds  or  that  is  an  after  development  of  the 
flower.     To  avoid   explaining  botanical  terms,   we  use 
the  word  in  the  latter  sense.     In  this  sense,  the  fruit 
serves  the  plant  by  attracting  animals  that  can  assist  in 
disseminating  the  seed. 

The  seed,  as  we  have  seen,  is  the  fecundated  and  ma- 
ture ovule  (144),  and  its  normal  office  is  reproduc- 
tion (16). 

156.  The  Fruit  Rarely  Develops  Without  Fecunda- 
tion of  the  germ  cell  of  the  ovule  (149).     Varieties  of 
the  apple  and  pear  have  appeared,  however,  in  which 
the  pulp  develops  without  seeds.     The  fruit  of  the  ba- 
nana is  almost  invariably  seedless.  The  cucumber,  grape, 
orange  and  fig  sometimes  develop  their  fruit  without 
fecundation  of  the  germ  cell.     These  instances  are  all 
exceptions  to  the  general  rule. 

157.  Seed  Production  Exhausts  the  Plant  far  more 
than  other  plant   processes.     The  seed  prepares   little 
or  no  food,  while  it  removes  from  other  parts  of  the 
plant  a  comparatively  large  amount  of  prepared  food, 
which  it  stores  up  in  a  concentrated  form  as  a  food  sup- 
ply for  the  embryo    (54).     Many  plants    (all  annuals 
and  biennials)  are  killed  the  first  time  they  are  permit- 


The  Fruit  and  the  Seed.  105 

ted  to  seed  freely,  and  perennials  are  often  weakened 
by  excessive  seding.* 

158.  Prevention   of   Seeding    Prolongs  the   Life   of 
Plants.     Many  annual  flowering  plants,  as  sweet  peas, 
dianthus,  etc.,  that  soon  perish  when  permitted  to  ma- 
ture their  seed,  continue  to  bloom  throughout  the  sum- 
mer if  the  flowers  are  persistently  picked.     The  yield 
of  cucumbers,  peas,  beans  and  other  garden  crops,  of 
which  the  product  is  gathered  immature,  may  be  con- 
siderably increased  by  preventing  the  ripening  of  seed. 

159.  Overbearing    Should    be    Prevented.     Certain 
varieties  of  some  of  our  cultivated  fruits,  as  the  apple, 
plum  and  peach,  tend  to  devote  an  undue  amount  of 
their  reserve  food  to  fruit  and  seed  production  in  fa- 
vorable seasons,  which  if  permitted,  results  in  enfeeble- 
ment  or  premature  death.     The  wise  cultivator  guards 
against  this  tendency  by  thinning  the  fruit  before  it  has 
made  much  growth,  thus  saving  the  tree  from  undue 
exhaustion  and  improving  the  quality  of  the  fruit  al- 
lowed to  mature. 

Thinning  should  be  done  as  early  as  the  fruits  can 
be  properly  assorted,  and  the  more  imperfect  ones 
should  always  be  removed.  The  proper  amount  of  thin- 
ning will  depend  upon  many  conditions,  as  age  and 
vigor  of  tree,  abundance  of  crop,  fertility  of  soil,  water 
supply,  etc.  It  must  be  determined  by  judgment  and 
experience.  Thinning  does  not  increase  the  total  crop 
but  it  may  enhance  its  value. 

160.  The     Maturing     of     Seeds     Injures     Fodder 
Crops.     The  food  value  of  straw,  from  which  the  ripe 

*  Double-flowered  varieties  of  the  annual  larkspur  (Delphin- 
ium), that  bear  no  seed,  have  become  perennial. 


106  Principles  of  Plant  Culture. 

grain  has  been  threshed,  is  comparatively  small,  and 
that  of  grass  and  other  crops  intended  for  coarse  fodder 
is  much  reduced  by  permitting  the  seed  to  ripen  be- 
fore cutting. 

161.  The  Ripening  of  Fruits.  Green  fruits  assist  the 
leaves  in  food  preparation  to  some  extent,  but  as  they 
begin  to  ripen,  the  process  is  reversed.     Carbonic  acid 
and  water  are  then  given  off,  while  oxygen  is  absorbed. 
Fruits  first  become  sour  from  the  production  of  acids 
which  disappear  in  part  at  a  later  stage,  while  sugar  is 
notably  increased.     Ripening  is  favored  by  warmth  and 
in  some  fruits  by  light. 

Some  fruits,  as  the  strawberry  and  peach,  increase 
rapidly  in  size  during  the  ripening  period,  provided 
the  water  supply  is  sufficient. 

Color  is  not  always  an  index  of  maturity.  Blackber- 
ries, currants  and  certain  other  fruits  improve  in  edible 
quality  for  some  time  after  assuming  their  mature  color. 

Most  fruits  that  have  attained  nearly  normal  size 
ripen  to  a  degree  when  detached  from  the  parent  plant. 
Pears  are  usually  improved  in  quality  if  picked  before 
maturity  and  ripened  in-doors.  The  grape,  however, 
fails  to  develop  its  sugar  if  prematurely  picked. 

After  a  certain  stage  of  maturity  is  reached,  all  vital 
processes  in  the  pulpy  part  of  the  fruit  cease,  and  dis- 
organization (decay)  begins,  unless  prevented  by  a  pre- 
servative process. 

SECTION  XII.     THE  GATHERING  AND  STORING  OF  SEEDS. 

162.  The   Stage   of   Maturity   at  which   Seeds   will 
Germinate  varies  greatly  in  different  plants  and  bears 


The  Gathering  and  Storing  of  Seeds.  107 

no  direct  relation  to  the  time  at  which  the  seeds  are  set 
free  from  the  parent  plant.  Seeds  of  the  tomato  will 
germinate  when  the  fruit  is  little  more  than  half  grown, 
and  those  of  the  pea  will  germinate  when  fit  for  table 
use.  Seeds  of  the  lemon  sometimes  germinate  within 
the  fruit.  On  the  other  hand,  seeds  of  the  thorn*  and 
juniper  rarely  germinate  until  the  second  spring  after 
their  production.  Seeds  of  many  annual  and  biennial 
plants,  as  the  cereals,  cabbage,  etc.,  may  germinate  as 
soon  as  set  free  by  the  parent  plant,  but  those  of  many 
annual  weeds  and  of  most  trees  and  shrubs  will  not 
germinate  until  some  months  afterward. 

Seeds  necessarily  gathered  immature  will  often  ripen 
sufficiently  for  germination  if  a  considerable  part  of 
the  plant  is  plucked  and  cured  with  them. 

Germinating  seeds  in  which  the  germination  process 
is  stopped  by  undue  drying  are  not  always  destroyed. 
Germination  may  be  resumed  on  access  to  water.  Seeds 
of  different  species  differ  widely  in  this  respect.  Those 
of  the  parsnip  and  carrot  cannot  endure  much  drying 
during  germination,  while  those  of  the  cereals  may  be 
repeatedly  dried  at  ordinary  temperatures  without  de- 
stroying their  vitality. 

163.  Immature  versus  Ripe  Seeds.  Seeds  not  fully 
grown  lack  a  part  of  their  normal  food  supply,  and 
their  embryo  is  probably  imperfectly  developed.  If 
capable  of  germination,  they  rarely  produce  vigorous 
plants.  As  a  rule,  the  most  vigorous  plants  come  from 
fully-matured  seeds.  Immature  seeds,  persistently  used, 
may  tend  to  reduced  vigor,  early  maturity,  dwarfness 

*  Crataegus. 


108 


Principles  of  Plant  Culture. 


and  shortened  life.  In  some  over-vigorous  plants,  as  the 
tomato,  slightly  immature  seed  may  tend  to  increased 
fruitfulness. 

Slightly  immature  seeds  usually  germinate  sooner 
than  fully  matured  ones. 

164.  The  Vitality  of  all  Seeds  is  Limited  by  Age, 
but  the  duration  of  the  vital  period  varies  greatly  in 
different  species.  Seeds  of  the  chervil  rarely  germinate 
if  much  more  than  one  year  old,  while  those  of  the 
gourd  family,  the  tomato  and  celery  often  germinate 
well  when  ten  years  old.  As  a  rule,  oily  seeds,  as  of  In- 
dian corn,  sunflower  and  the  cabbage  family  (cabbage, 
cauliflower,  kohl-rabi,  Brussels  sprouts,  ruta-baga,  rape, 
turnip,  mustard)  are  shorter  lived  than  starchy  seeds, 
as  wheat  and  rice.  Oily  seeds  cannot  safely  be  stored 
in  bulk  in  large  quantities,  except  in  cool  weather.  The 
following  table  gives  the  average  period  during  which 
the  seeds  named  are  reliable  for  germination,  when 
properly  cared  fcr*:* 


Dorati 
Germinatin 
Average. 
Years. 

Artichoke    6 
Asparagus     5 

>n  of 
'  Power 

Extreme 
Yeart. 

10 
8 
10 

8 
6 
10 
10 
10 
10 
9 
10 
10 
10 
6 
1 
1 
10 
5 
9 
9 
10 
10 
10 

Dura 
Germinati 
A 
Y 

Gumbo    or    Okra  
Hop     

ion  of 
ng  Power, 
v.  Ext'm. 
n      Yn. 
5      10 
2         4 

5     10 
3       9 
4      9 
5       9 
2       7 
5     10 
6     10 
4      9 
2       7 
2      4 
3       9 
3       8 
6     10 
3       8 
2      8 
1       7 
5       7 
6     10 
3       6 
4      9 
5     10 

fc    Cie, 

Kohl-Rabi 

Bean  —  Kidney         
Bean  —  Soy    
Beet     

3 
2 
6 
6 
5 

7 

5 
8 
8 
1 
1 
6 
1 
5 
5 
10 

10 

Leek    
Lentils     
Lettuce    . 

Maize  or  Indian  corn  
Melon     Musk 

Broccoli    
Cabbage 

Melon    Water 

Cardoon    

Mustard  —  Black   or  Br'n. 

Cauliflower     
Celery 

Chervil  2  or 

Pea 

Chervil  —  Sweet-scented    . 
Chervil  —  Turnip-rooted     . 
Corn    Salad    

Pumpkin    

Rhubarb    

Salsify     ...    . 

Cress  —  American    
Cress  —  Common    Garden. 
Cress  —  Water     
Cucumber  —  Common     
Eggplant     
Endive     

Sea-kale    

Spinach—  Prickly-seeded  . 
Squash    

Strawberry 

Tomato    

Turnin     . 

*  From    "The    Vegetable 

Garden,"    Vilmorin.    Andrieux    t 

Paris 


The  Gathering  and  Storing  of  Seeds.  109 

165.  Conditions    Affecting    the    Duration    of    Seed 

Vitality.  A  uniform  degree  of  humidity  and  tempera- 
ture tends  to  prolong  the  vital  period  of  seeds  by  caus- 
ing little  drain  upon  the  life  of  the  living  cells.  Seeds 
deeply  buried  in  the  ground  are  often  capable  of  ger- 
mination at  a  great  age,  and  kidney  beans  at  least  one 
hundred  years  old,  taken  from  an  herbarium,  are  said 
to  have  germinated.  In  these  cases,  the  seeds  were  sub- 
jected to  few  variations  in  humidity  and  temperature. 
Seeds  usually  retain  vitality  longer  when  not  re- 
moved from  their  natural  covering,  probably  because 
they  are  thus  exposed  to  fewer  changes  of  humidity 
and  temperature.  Timothy  seeds,  that  became  hulled  in 
threshing,  lose  vitality  sooner  than  those  that  escape 
hulling,  even  when  the  twro  sorts  have  been  kept  in  the 
same  bag.  Indian  corn  is  said  to  retain  vitality  longer 
on  the  cob  than  shelled,  and  longer  when  the  ear  is 
unhusked  than  if  husked. 

166.  Moisture  is  an  Enemy  to  Stored  Seeds,  except 
for  the  class  that  requires  stratification  (169).     A  little 
moisture  in  stored  seeds  is  very  liable  to  cause  the  de- 
velopment of  fungi  (moulds)  that  may  destroy  the  em- 
bryo.    Damp  seeds  are  also  liable  to  be  destroyed  by 
freezing.     It  is  important  that  seeds  be  dried  promptly 
after  gathering,  for  if  mould  once  starts,  subsequent 
drying  may  not  destroy  the  fungus;  the  latter  may  re- 
sume growth  as  soon  as  the  seed  is  planted,  thus  en- 
feebling or  destroying  the  embryo  before  it  has  time 
to  germinate.     Drying  by  moderate  artificial  heat  (not 
higher  than  100°  F.)  is  wise  with  seeds  gathered  in  cold 
or  damp  weather. 


110  Principles  of  Plant  Culture. 

Seeds  are  shorter-lived  in  warm  than  in  cooler  cli- 
mates. 

The  most  satisfactory  method  of  preserving  seeds  in 
quantity  is  to  inclose  them  in  bags  of  rather  loose  tex- 
ture and  of  moderate  size,  and  to  store  them  in  a  cool, 
dry  and  airy  place. 

167.  Age  of  Seed  as  Affecting  the  resulting  Crop. 
Seeds  grown  the  same  or  the  preceding  season  produce, 
as  a  rule,  more  vigorous  plants  than  older  seeds.     They 
may  not,  however,  in  all  cases  produce  plants  that  are 
most  productive  of  fruit  or  seed,  for  excessive  vigor  is 
generally    opposed    to    reproduction.     Cucumber    and 
melon  plants  grown  from  seed  three  or  four  years  old 
are  often  more  fruitful  than  those  from  fresh  seeds. 
In  crops  grown  for  parts  other  than  fruit  or  seed,  fresh 
seeds  are  undoubtedly  preferable,  but  in  crops  grown 
for  seed  or  fruit,  fresh  seed  may  not  always  give  as 
large  returns  as  seed  of  some  age.     This  subject  needs 
further  investigation. 

168.  How    Drying   Affects   the   Vitality   of    Seeds. 
The  vigor  of  seeds  is  probably  never  increased  by  dry- 
ing them,  but  the  seeds  of  most  annual  and  biennial 
plants   may   become    air-dry   without  material   loss   of 
vitality.     The  seeds  of  many  shrubs  and  trees,  however, 
lose  vitality  rapidly  by  such  drying  and  those  of  some 
species  are  destroyed  by  it.     In  nature,  seeds  of  the 
latter  class  are  usually  dropped  from  the  parent  plant 
before  becoming  dry  and  are  soon  covered  by  leaves  or 
other  litter  that  keeps  them  moist.     Nurserymen  either 
plant  such  seeds  as  scon  as  they  are  ripe,  or  if  of  spe- 


Decline  of  Growth  and  the  Rest  Period.         Ill 

cies  that  do  not  germinate  as  soon  as  ripe,  they  imitate 
nature  by  the  process  known  as 

169.  Stratification  of  Seeds.     This  consists  in  mix- 
ing the  freshly-gathered  seeds  with  sand,  taking  care 
that  the  sand  is  kept  moist  until  the  time  for  sowing 
arrives.     Large  quantities  of  seeds  may  be  stratified  in 
boxes,  by  placing  the  moist  sand  and  seeds  in  alternate 
layers,  or  the  layers  may  be  built  up  in  a  pile  on  the 
ground.     The  sand  should  be  coarse  enough  to  admit 
some  passage  of  air  between  the  particles  and  to  give 
perfect  drainage.     The  layers  should  not  much  exceed 
an  inch  in  thickness,  except  for  the  larger  seeds,  and  the 
number  of  layers  should  not  be  so  large  as  to  prevent 
proper  aeration  of  the  mass.     Small  quantities  of  seeds 
may  be  mixed  with  sand  or  porous  loam  in  flower-pots. 
Moisture  may  be  maintained  in  the  boxes  or  pots  by 
burying  them  a  foot  or  more  deep  in  the  soil  in  a  well- 
drained  place,  or  by  storing  them  in   a  moist   cellar. 
Care  is  necessary  to  keep  mice  and  other  vermin  from 
stratified  seeds.     It  is  well  to  cover  pots  in  which  valu- 
able seeds  are  stratified,  with  a  sheet  of  tin  or  zinc; 
metal  labels  are  best  for  distinguishing  different  sorts 
of  seed.     The  seeds  should  remain  stratified  until  sow- 
ing time,  when  they  may  be  sifted  out  of  the  sand  or 
sown  with  it,  as  is  more  convenient.     Seeds  that  do  not 
germinate  well  until  the  second  spring  after  maturity 
(162)  are  commonly  left  in  stratification  until  that  time. 

SECTION   XIII.     THE  DECLINE   OP    GROWTH   AND   THE 
REST  PERIOD. 

170.  Annual  plants  usually  perish  soon  after  matur- 
ing their  seed.     In  other  plants,  a  certain  period  of 


112  Principles  of  Plant  Culture. 

vital  activity  is  followed  by  one  in  which  growth  gradu- 
ally declines  until  it  almost  or  entirely  ceases.  In 
woody  plants,  the  cells  become  thickened  and  a  part 
of  the  rudimentary  leaves  change  to  bud-scales,  which 
inclose  the  growing  point  (127).  In  deciduous  (de- 
cid'-u-ous)*  trees  and  shrubs,  the  chlorophyll  and 
starch,  with  mcst  of  the  potash  and  phosphoric  acid 
contained  in  the  leaves  are  withdrawn  into  the  woody 
parts  (126),  while  the  leaves  themselves  are  detached  and 
fall.  The  root-hairs  also  die  in  many,  if  not  all  plants. 
The  leaves  of  many  trees  and  shrubs  assume  striking 
colors  as  they  approach  maturity.  In  perennial  herbs, 
the  nutritive  matters  in  the  foliage  and  stem  are  with- 
drawn to  the  underground  parts.  A  period  of  almost 
complete  repose  ensues,  during  which  the  plant,  owing 
to  the  dormant  condition  of  its  protoplasm,  is  able  to 
endure  without  harm  extremes  of  temperatures  or  dry- 
ness  that  would  be  fatal  in  its  active  state. 

Growth  ceases  in  many  trees  and  shrubs  earlier 
than  is  often  supposed.  Most  orchard  and  forest  trees 
of  mature  age  grow  little,  if  any,  after  midsummer  in 
the  temperate  zones.  Cultivation,  mulching,  manuring 
and  wet  weather  tend  to  prolong  the  growth  period 
(199). 

171.  The  Rest  Period  is  Not  Peculiar  to  the  Tem- 
perate Zones,  but  occurs  in  the  tropics  as  well.  It  can 
be  ascribed  in  part  to  the  change  of  seasons,  as  a  few 
familiar  examples  will  indicate.  Tubers  of  the  earlier 
varieties  of  the  potato,  that  ripen  in  northern  countries 

*  Deciduous  trees  and  shrubs  are  those  of  which  the  leaves 
perish  at  the  beginning  of  the  rest  period. 


Decline  of  Growth  and  the  Rest  Period.         113 

by  the  beginning  of  August,  do  not  sprout  if  left  in 
the  ground  till  October,  but  if  stored  in  a  cellar  during 
winter  at  a  temperature  little  above  freezing,  they 
often  begin  to  sprout  in  March.  Bulbs  of  the  crocus, 
tulip,  narcissus,  crown  imperial,  etc.,  that  form  in 
spring,  lie  dormant  in  the  warm  soil  during  summer 
and  early  autumn,  but  start  vigorously  in  the  colder 
soil  of  the  late  autumn  or  the  succeeding  spring.  The 
buds  of  many  trees,  that  form  in  summer  for  the  next 
year's  foliage  and  flowers,  remain  dormant  during  the 
hot  weather  of  August  and  September,  to  push  vigor- 
ously in  the  first  warm  days  of  spring.  The  rest  period 
is  to  be  regarded  as  a  normal,  if  not  a  necessary  factor 
of  plant  life. 

172.  Most   Plants  Under  Glass  Require   Rest  from 
time  to  time,  or  they  do  not  thrive.     The  rest  is  pro- 
vided either  by  keeping  them  at  a  lower  temperature 
than  is  favorable  to  growth,  or  by  submitting  them  to  a 
degree  of  dryness  that  prevents  growth.     The  latter  is 
preferable  for  plants  native  in  the  tropics,  where  they 
naturally  lie  dormant  during  the  dry  season. 

173.  The  Time  of  Leaf  Fall  is  an  Index  of  Wood 
Maturity  in  healthy  deciduous  trees  and  shrubs.     In 
these,  the  coloring  and  fall  of  the  leaves  in  autumn  is 
not  necessarily  due  to  frost,  but  results  from  the  dor- 
mant condition  that  accompanies  maturity.     As  a  rule, 
the  more  mature  leaves  are  precipitated  by  the  first  au- 
tumn  frost.     Those  less   mature   usually  remain   until 
the  more    severe    frosts.     In    trees  with   well-ripened 
wood,  the  leaves  at  the  tip  of  the  shoots  usually  fall 
before,  or  not  later  than,  these  en  the  older  parts  of 


114  Principles  of  Plant  Culture. 

the  tree.  With  poorly-matured  wood  the  reverse  is  the 
case.  In  a  few  deciduous  trees,  as  the  beech  and  some 
oaks,  many  of  the  mature  leaves  remain  on  through  the 
winter. 

174.  Hardiness  Depends  upon  the  Degree  to  which 
the  Dormant  State  is  Assumed.     Since  the  most  se- 
vere climatic   extremes  come  during  the  natural   rest 
period  of  plants  the  ability  of  the  plant  to  endure  these 
extremes  depends  upon  the  extent  to  which  the  pro- 
toplasm becomes  dormant  during  the  decline  of  growth. 
As  a  rule,  a  given  plant  is  hardy   (10)    in  a  locality 
in  which  the  duration  and  the  warmth  of  the  growing 
season  are  sufficient  to  complete  and  fully  mature  its 
normal  amount  of  growth.     Varieties  of  the  apple  and 
other  trees,  that  so  far  complete  their  growth  in  any 
given  locality  that  their  leaves  fall  before  hard  frosts, 
are  rarely  injured  in  winter,  while  those  that  continue 
growth  until  their  foliage  is  destroyed  by  freezing  suf- 
fer in  severe  winters.     Deciduous  trees   are  liable  to 
destruction  in  severe  winters  in  a  climate  where  none  of 
the  leaves  fall  before  hard  frosts,  as  is  the  case  with 
the   peach,   apricot    and  nectarine   in   northen  United 
States. 

175.  Individual   Plants  Cannot  Adjust  Themselves 
to  a  New  Environment,  except  to  a  slight  extent.     The 
power  to  complete  the  annual  growth  processes  and  be- 
come sufficiently  dormant  to   endure  the  rigor  of  the 
rest  period  in  any  given  locality  is  inherited,  and  not 
acquired.     We    are,    therefore,    able   to   do   very   little 
toward  inuring  or  acclimatizing   (ac-cli'-ma-tiz-ing)   in- 
dividual plants  to  an  environment  to  which  they  were 


Decline  of  Growth  and  the  Rest  Period.         115 

not  adapted  by  nature.  We  may,  however,  through  the 
variations  of  offspring  (18),  secure  varieties  in  some 
cases  that  can  endure  an  environment  which  the  parents 
could  not  endure. 

176.  Plant  Processes  during  the  Rest  Period  may 
not  entirely  cease.  Although  food  preparation  is  wholly 
suspended,  root  growth  and  the  callusing   (72)    of  in- 
jured root  surfaces  proceed  to  some  extent  during  win- 
ter in  unfrozen  layers  of  soil;  and  in  sufficiently  mild 
weather,  the  reserve  food  in  the  stem  gradually  moves 
in  the  direction  of  the  terminal  buds. 

177.  Cuttings    (358)   of  Woody  Plants  are  Prefer 
ably   Made  in  Autumn  in  climates  of  severe  winters 
and  buried  in  the  ground  below  the  limit  of  hard  freez- 
ing, in  order  that  callusing   (72)    and  the  transfer  of 
food  may  make  some  progress  before  the  final  planting. 

178.  The  "Turn  of  the  Year."     Toward  the  close  of 
the  dormant  season,  vegetation,  as  if  benefited  by  the 
rest,  is  prepared  to  start  with  renewed  vigor,  even  at 
moderate  temperatures.     Buds,  that  remained  dormant 
during  the  latter  part  of  the  previous  summer,  push 
into  growth  with  the  first  warm  days  of  spring,  and 
many  seeds,  that  could  not  be  induced  to  germinate  the 
preceding  autumn,  start  with  vigor  as  soon  as  the  soil 
is  sufficiently  warm. 

The  cause  for  this  energetic  resumption  of  plant 
growth  after  the  rest  period  is  not  well  understood, 
but  exposure  to  cold,  in  the  case  of  temperate  plants, 
and  to  prolonged  dryness  in  that  of  tropical  ones, 
doubtless  explains  it  in  part,  for  it  is  well  known  that 
potato  tubers  may  be  induced  to  start  their  buds  soon 


116  Principles  of  Plant  Culture. 

after  maturity  by  exposing  them  to  the  sun  a  few  days, 
or  by  placing  them  for  a  like  time  in  a  refrigerator 
containing  ice.  By  these  means,  the  farmers  of  Ten- 
nessee grow  a  second  crop  of  potatoes  in  the  latter  part 
of  summer  and  during  autumn. 

Plants  under  glass  usually  thrive  better  after  mid- 
winter than  before,  and  the  most  favorable  time  to 
plant  seeds  of  greenhouse  plants  is  toward  the  close  of 
the  natural  rest  period. 

179.  The  Round  of  Plant  Life  has  now  been  traced, 
from  the  first  swelling  of  the  planted  seed,  through  the 
development  of  the  embryo  into  the  plantlet,  the  pene- 
tration of  the  root  into  the  dark  and  damp  soil  cavities, 
the  absorption  and  conduction  of  water  with  its  food 
materials  in  solution,  co-operating  with  the  sunlight 
and  carbonic  acid  in  the  mysterious  laboratory  of  the 
leaf,  in  building  up  the  plant  body  into  node  and  inter- 
node,  leaf,  bud,  branch,  flower,  fruit  and  seed;  through 
growth  decline,  leaf  fall  and  winter  sleep,  to  the  re- 
newed vigor  of  another  springtime. 

In  our  study  of  the  round  of  plant  life,  we  have  as- 
sumed the  environment  to  be  favorable.  But  in  the 
practical  culture  of  plants,  we  are  constantly  meeting 
with  adverse  conditions  of  environment.  Talent  for 
plant  culture  lies  in  the  ability  to  discern  these  adverse 
conditions  by  the  appearance  of  the  plant,  and  in  know- 
ing how  to  correct  them.  We  will,  therefore,  next  con- 
sider the  plant  as  affected  by  unfavorable  conditions  of 
environment. 


Decline  of  Growth  and  the  Best  Period.         117 

The  following  books  are  recommended  for  reading  in 
connection  with  the  preceding  chapter:  How  Plants 
Grow,  Gray;  Lessons  in  Botany,  Gray;  Botanical  Text- 
Book,  Gray;  A  Treatise  on  the  Physiology  of  Plants, 
Sorauer;  The  Soil,  King;  The  Fertility  of  the  Land, 
Roberts. 


CHAPTER  III. 

THE  PLANT  AS  AFFECTED  BY  UNFAVORABLE 
ENVIRONMENT. 

180.  Factors  of   Environment.     The  plant  environ- 
ment is  mostly   comprehended  by  the  terms,   climate, 
soil,  animals  and  other  plants.     But  as  these  are  more 
or  less  complex  influences,  it  is  well  to  analyze  them 
and   to   consider  separately  the  component  factors  of 
each. 

SECTION  I.     THE  PLANT  AS  AFFECTED  BY  UNFAVORABLE 
TEMPERATURE. 

A— THE  PLANT  AS  AFFECTED  BY  EXCESSIVE  HEAT. 

181.  Transpiration    Increases    with    the    Degree    of 

Heat.  The  most  common  effect  of  heat  upon  plants  is 
the  drooping  of  the  foliage,  due  to  excessive  transpira- 
tion (74).  With  insufficient  water,  this  may  occur  at 
a  temperature  that  is  normal  for  the  plant.  But  with 
a  water  supply  that  is  sufficient  at  ordinary  tempera- 
tures, transpiration  may  be  so  much  increased  by  an 
overheated  atmosphere  that  the  roots  are  unable  to  sup- 
ply the  plant  with  sufficient  water,  hence  the  cells  be- 
come partially  emptied  and  the  foliage  droops.  Her- 
baceous plants  in  an  overheated  greenhouse  or  hotbed 
are  sometimes  so  prostrated  from  excessive  loss  of  water 
as  to  appear  dead,  but  unless  the  heat  has  been  suffi- 
cient to  destroy  their  protoplasm,  or  the  heated  period 
has  been  protracted,  they  will  recover  when  normal 
temperature  and  water  supply  are  restored. 


Plants  as  Affected  ~by  Heat.  119 

182.  Evergreen  Trees  are  sometimes   Destroyed  by 
Untimely  Warm  Weather  in  spring.     With  a  soil  so 
cool  that  the  roots  are  inactive,  a  sudden  rise  of  atmos- 
pheric temperature,  especially  if  accompanied  by  a  dry- 
ing wind,  may  so  far  reduce  the  water  in  the  leaves  of 
evergreen  trees  as  to  cause  death  of  the  foliage  and  even 
of  the  trees  themselves.     This  most  frequently  happens 
in   the   seed-bed,    in   compact   nursery    plantations,    or 
with  recently  transplanted  evergreen  trees.     It  is  most 
disastrous  on  poorly-drained  clay  soils  that  have  a  sunny 
exposure,  and  at  times  when  the  ground  is  deeply  frozen. 

The  preventives  to  be  observed  are,  a,  means  that 
favor  prompt  thawing  of  the  ground,  as  thorough  drain- 
age and  not  too  close  planting;  &,  means  that  prevent, 
in  a  measure,  exposure  to  the  sun,  as  planting  on  a 
northern  slope  or  shading  the  trees  (414)  ;  c,  means 
that  tend  to  prevent  deep  freezing  of  the  soil,  as  pro- 
viding wind  breaks  which  tend  to  retain  the  snow  (203). 

183.  A  Temperature  of  122°  F.  is  Fatal  to  the  Pro- 
toplasm of  most  land  plants.     Aquatic  plants  and  the 
more  watery  parts  of  land  plants  perish  at  a  somewhat 
lower   temperature.     Watery    fruits,    as    tomatoes    and 
gooseberries,  and  the  younger  leaves  of  deciduous  trees, 
are  sometimes  destroyed  by  exposure  to  the  sun's  rays 
in  hot  weather.     An  occasional  sprinkling  of  the  plants 
and  of  the  soil  about  them  will  usually  prevent  this 
result. 

184.  Plants  Under  Glass  should   Not  be  Sprinkled 
in  Bright  Sunshine.     Drops  of  water  upon  the  leaves 
of  plants  often  act  as  lenses  in  converging  the  rays  of 
the  sun,  and  in  a  closed  greenhouse  or  hotbed  may  cause 


120  Principles  of  Plant  Culture. 

a  heat  that  is  fatal  to  the  foliage  beneath  them.  This 
may  explain  the  brown  spots  so  often  observed  upon  the 
leaves  of  indoor  plants  that 
have  been  sprinkled  in  bright 
sunlight.  Sometimes,  but  rare- 
ly, this  trouble  occurs  in  the 
open  air. 

185.  Sun-Scald  is  the  term 
applied  to  an  affection  of  the 
trunk  and  larger  branches  of 
certain  not  quite  hardy  trees, 
usually  upon  the  south  or 
southwest  side,  in  which  the 
bark  and  cambium  layer  (68) 
are  more  or  less  injured  (Fig. 
58).  In  severe  cases,  the  cam- 
bium is  totally  destroyed,  and 
the  loosened  bark  splits  longi- 
tudinally or  becomes  detached. 
The  effect  is  apparently  the 
same  as  when  a  tree  is  exposed 
to  the  heat  of  a  fire.  Sun-scald 
is  most  common  in  young  trees, 
especially  in  those  recently 
transplanted  or  overpruned. 
It  appears  to  be  due,  in  some 

FIG.  58.      Showing    effects    of  ,        . .  ,, 

sun-scaid      on      trunk      and  cases,  to  the  superheating  oi 

branches       of       silver       maple  . 

tree,  Acer  dasycarpum.  the  cambium  in  summer — in 

others  to  a  return  of  severe  freezing  weather  after  a 
period  sufficiently  warm  to  excite  the  cambium  cells  to 
activity.  A  preventive  is  to  shade  the  trunk  and  larger 


Plants  as  Affected  by  Cold.  121 

branches  by  inclosing  them  with  straw  or  similar  ma- 
terial, or  with  a  lath  screen  (Fig.  59). 

186.  Potato  Foliage  is  often  Injured  by  Sun  Heat  in 
summer,  as  is  shown  by  the  browning  of  the  leaves  from 
the  tip  and  edges  toward  the  cen- 
ter, or  on  the  border  of  holes  made 
by  insects.  This  affection,  known 
as  tip-burn,  is  due  to  the  destruc- 
tion of  protoplasm  in  the  cells  and 
is  often  mistaken  for  fungus  work. 
It  is  most  serious  in  dry  seasons.  No 
remedy  for  it  is  known,  but  it  may 
be  in  part  avoided  by  selecting  va- 
rieties least  subject  to  it. 

B — THE  PLANT  AS  AFFECTED  BY 
EXCESSIVE   COLD. 

187.  The  Immediate  Effect  of 
Cooling  the  Plant  is  to  check  the 
activity  of  its  vital  processes.  When 
a  certain  degree  of  cold  is  reached, 
the  protoplasm  loses  its  power  to 
imbibe  water  (62)  ;  hence  the  plant 
tissues  become  less  turgid,  and  the 
foliage  droops  somewhat  (102). 
With  a  sufficient  reduction  of  tem- 
„  ->-  perature,  ice  crystals  form  within 

inclosed     in  r 

ith  screen.  the  tissues  and  the  succulent  parts 

of  the  plant  assume  a  glassy  appearance.  The  foliage 
of  many  plants,  as  celery,  parsnip,  etc.,  assumes  an 
abnormal  position  when  frozen. 


122  Principles  of  Plant  Culture. 

188.  The  More  Water  Plant  Tissues  Contain,  the 
Sooner  they  Freeze.     Since  the  water  of  plants  is  not 
pure,  but  is  a  solution  of  various  substances,  it  does 
not   freeze  at  the  freezing  point  of  pure  water    (325 
F.),  but  at  a  lower  temperature,  determined  by  the  de- 
gree of  concentration  of  the  solution,  or  the  intimacy 
with  which  it  is  combined  with  the  tissues  of  the  plant. 
The  more  thoroughly  dormant  the  condition  of  a  plant, 
or  part  of  a  plant,  the  less  water  does  it  contain,  and 
the  better  is  it  able  to  endure  cold  (174). 

189.  The  Power  of  Plants  to  Endure  Cold  depends 
upon   various    conditions,    aside    from    the    amount   of 
water  contained,  as 

a — Heredity.  Plants  by  nature  possess  widely  differ- 
ing powers  to  endure  cold.  The  Anoectochilus  (a-ncec'- 
to-chi'-lus)  perishes  when  exposed  for  a  considerable 
time  to  a  temperature  of  42°  F.,  while  other  plants,  as 
the  common  chickweed,*  are  uninjured  by  prolonged 
cold,  far  below  the  freezing  point  (175). 

b—The  rate  of  thawing  of  the  frozen  tissues.  The 
more  slowly  the  thawing  takes  place,  the  less  likely  is 
the  frozen  part  to  suffer  injury.  Many  bulbs,  tubers 
and  roots  which  survive  the  severest  winters  within  the 
soil,  where  they  thaw  slowly,  are  destroyed  by  moderate 
freezing  if  quickly  thawed.  Frost-bitten  plants  are  sel- 
dom injured  when  sheltered  from  the  morning  sun  by 
a  dense  fog,  which  causes  them  to  thaw  slowly.  Apples, 
covered  in  the  orchard  in  autumn  by  leaves,  sometimes 
pass  a  severe  winter  with  little  harm. 

*  Stellaria  media. 


Plants  as  Affected  ~by  Cold.  123 

When  the  water  that  is  withdrawn  from  the  tissues 
in  the  freezing  process,  is  gradually  set  free  by  slow 
thawing,  it  may  be  absorbed  by  them  again  and  little  or 
no  harm  results. 

G—The  length  of  time  the  tissues  remain  frozen.  A 
comparatively  slight  degree  of  frost,  if  prolonged,  may 
act  more  injuriously  than  a  severer  degree  of  shorter 
duration.  Prolonged  freezing  is  especially  injurious 
when  the  frozen  parts  are  subjected  to  drying  wind, 
which  evaporates  their  water,  while  the  frozen  condi- 
tion prevents  movements  of  their  fluids. 

d—The  frequency  with  which  freezing  and  thawing 
are  repeated.  Frequent  slight  freezing  and  thawing 
are  far  more  injurious  than  a  prolonged  frozen  condi- 
tion, even  though  the  latter  occurs  at  a  much  lower  tem- 
perature. Winter  wheat  and  rye,  and  strawberry  beds 
are  often  more  damaged  in  mild  winters,  in  which  freez- 
ing and  thawing  weather  alternate,  than  in  more  severe 
ones,  when  the  temperature  is  mostly  below  freezing. 
The  chief  damage  is  usually  dene  to  these  crops  in  late 
autumn  and  early  spring. 

Q—The  previous  treatment  of  the  plant.  Plants  grown 
by  artificial  heat  may  be  far  less  able  to  endure  cold 
than  others  of  the  same  varieties  grown  in  the  open  air, 
possibly  owing  to  the  more  succulent  condition  of  the 
former.  Gardeners  harden  plants  grown  under  glass, 
by  gradually  exposing  them  to  the  cooler  out-door  at- 
mosphere, before  removing  them  to  the  open  ground. 

i—The  treatment  of  the  frozen  tissues.  Handling 
plants,  fruits  or  vegetables  while  frozen  greatly  aggra- 
vates the  damage  from  frost,  probably  because  the  han- 


124  Principles  of  Plant  Culture. 

dling  increases  laceration  of  the  cells  by  the  ice  crystals 
within  them.  '-  .  ••"' 

190.  Frost-Injured    Plants,    Fruits    or    Roots    May 
often    Be    Saved    from    serious    damage,    if    promptly 
placed  under  conditions  that  cause  the  slowest  possible 
thawing  of  the  tissues,  as  shading  from  the  sun's  rays, 
immersing  in  ice  water  or  covering  with  snow.     They 
should  be  handled  as  little  and  as  carefully  as  possible 
while  frozen.     Sprinkling  with  cold  water  is  often  suf- 
ficient to  restore  frost-bitten  plants. 

Aside  from  the  death  of  tender  plants  by  cold,  more 
or  less  hardy  species  suffer  injury  in  a  variety  of  ways, 
of  which  the  following  are  examples: 

191.  Destruction    of   Terminal    Buds   by   Cold.     In 
plants  which  do  not  mature  their  terminal  buds  in  au- 
tumn, as  the  raspberry,  sumac,  grape,  etc.,  destruction 
of  the  tips  of  growing  shoots  by  frost  is  a  regular  oc- 
currence in  climates  of  severe  winters.     The  distance 
which  the  shoots  are  killed  back  depends  upon  the  suc- 
eulency  of  the  growth,  the  severity  of  the  winter  and 
the  natural  power  of  the  plant  to  endure  cold.     Plants 
thus  affected  are  not  always  to  be  regarded  as  tender, 
since  they  often  grow  wild  in  climates  of  very  severe 
winters. 

192.  The  Darkening  of  the  Wood   (black-heart)   of 
certain  trees,  as  the  pear,  in  climates  of  severe  winters, 
appears  to  be  a  chemical  effect  of  the  cold.     It  begins 
at  the  center  of  the  stem  and  in  extreme  cases  may  ex- 
tend clear  to  the  cambium,  .when  the  bark  ceases  to 
adhere,  and  the  tree  or  branch  thus  affected  dies.     In 
stone    fruits,  this  trouble   is  often   accompanied   by  a 


Plants  as  Affected  by  Cold.  125 

flow  of  gum.  If  the  coloring  of  the  wood  does  not  ex- 
tend to  the  cambium,  the  tree  or  branch  may  survive, 
but  the  first  season's  growth  thereafter  is  generally 
feeble  and  the  fruit  or  the  seed  crop  often  fails.  Dur- 
ing the  second  season,  healthy  growth  may  be  resumed, 
but  the  heart-wood  is  rarely  or  never  restored  to  its 
normal  color.  Black-heart  often  results  from  other 
causes  than  cold,  as  from  bacteria  that  gain  access  to 
the  heart-wood  through  wounds  (418). 

Other  chemical  changes  result  from  cold,  as  the 
sweetening  of  potato  tubers  when  chilled,  the  removal 
of  astringency  from  the  wild  grape  and  persimmon, 
and  the  heightening  of  the  flavor  of  the  parsnip. 

193.  Tree    Trunks    are    sometimes    Split    Open    by 
Severe  Freezing,  the  split  remaining  open  until  the  re- 
turn of  mild  weather.     This  most  often  occurs  in  hard- 
wooded,  deep-rooted  deciduous  trees,  as  the  oak,  and 
appears  to  result  from  the  more  rapid  contraction  of 
the  outer  layers  of  the  wood  in  a  sudden  fall  of.  tem- 
perature.    The  rents  are  usually  overgrown  by  the  next 
annual  wood  layer    (70). 

The  splitting  down  of  the  main  branches  of  certain 
varities  of  the  apple  tree  appears  to  be  favored  by  the 
expansive  force  of  ice  in  narrow  crotches,  which  retain 
snow  and  water.  Varities  the  branches  of  which  leave 
the  trunk  at  a  wide  angle  are  not  subject  to  this  trouble. 

194.  Bark-Bursting   on  the  trunks   of  young  apple 
trees  often  occurs  when  freezing  weather  overtakes  late- 
growing   and   hence    poorly-matured   wood.     In   severe 
cases,  the   bark  splits   longitudinally   entirely   through 
the  cambium  layer  and  from  the  ground  to  the  lower 


126  Principles  of  Plant  Culture. 

branches;  and  the  bark  is  loosened  from  the  wood 
nearly  or  quite  around  the  trunk.  Such  trees  are  prac- 
tically ruined,  but  trees  slightly  injured  by  bark  burst- 
ing may  fully  recover. 

Bark-bursting  is  usually  most  severe  on  deep,  rich, 
moist  soil  and  in  seasons  that  favor  late  growth,  or  in 
which  freezing  weather  occurs  unusually  early.  Late- 
growing  varieties  are  most  subject  to  it.  Its  occurrence 
is  lessened  by  treatment  that  favors  early  maturity  of 
the  wood  (199,  200). 

195.  Root-Killing   of  trees.     "When  a  very   dry   au- 
tumn passes  to  winter  without  rain  or  snow,  the  surface 
layers  of  the  soil  sometimes  freeze  so  severely  as  to  de- 
stroy the  roots  of  trees.     Root-killing  is  usually  most 
serious  on  light  soils,  and  on  one-year-old,  root-grafted 
(391)  nursery  trees,  especially  when  grafted  with  short 
cions  (386).    With  very  severe  freezing  on  bare  ground, 
root-killing  sometimes  occurs  on  soil  well  supplied  with 
water.     The  destruction  of  the  roots  may  be  complete 
or  only  partial.     In  the  latter  case,  the  tree,  if  of  a 
vigorous    variety,    may    largely    outgrow    the    trouble, 
though  complete  recovery  is  rare. 

Treatment  that  prevents  late  growth  (199,  200),  or 
mulching  the  ground  about  trees  tends  to  avert  root- 
killing. 

196.  Flower-Buds    are    often    Destroyed    by    Cold 
while  other  parts  of  the  plant  are  uninjured.     This  fre- 
quently occurs  in  the  peach,  cherry,  apricot,  nectarine 
and  certain  species  of  the  plum  in  climates  of  rather 
severe   winters,    especially   after    the    buds   have    been 
somewhat     excited     by     unseasonable    warm     weather. 


During  the  Dormant  Period.  12t 

Flower-buds  thus  destroyed  are  dark-colored  at  the 
center.  Often  only  a  part  of  the  embryo  flowers  on  a 
tree  are  destroyed. 

197.  Flowers  are  Especially  Sensitive  to  Cold.  Fruit 
crops  are  usually  wholly  or  in  part  cut  off  if  a  slight 
frost  occurs  during  bloom,  and  in  certain  fruits,  as  the 
apricot    and  some   species    of  the   plum,   the   blossoms 
sometimes  appear  to  be  destroyed  by  a  degree  of  cold 
that  does  not  descend  to  the  freezing  point,   possibly 
through  interference  with  pollination  or  pollen  germi- 
nation  (150).     When  the  freezing  is  accompanied  with 
snow,  however,  open  flowers  may  escape  without  harm, 
probably    owing   to   the   slow    extraction   of   the    frost 
(189  b). 

198.  Low  Plants  are  often  Destroyed  by  Ice,  espe- 
cially when  the  ice  layer  forms  in  direct  contact  with 
the  soil  about  them  and  remains  for  a  time  after  the 
return  of  warm  weather.     The  same  effect  results  some- 
times from  a  covering  of  snow,  of  which  the  top  has 
formed  into  a  crust  of  ice.     Winter  grain,  strawberry 
plants  and  lawn  grass  are  often  smothered  in  this  way. 
Surface   drainage  of  ground  devoted  to  such  crops  is 
highly  important. 

SECTION  II.    METHODS  OP  AVERTING  INJURY  BY  COLD. 

A  — DURING  THE  DORMANT  PERIOD. 

B.—By    Treatment   of  the   Soil. 

199.  A  Dry  Soil   Favors  Wood  Maturity,  while  an 
abundant  water  supply  retards  it.     Soil  treatment  that 
restricts  the  water  supply  toward  the  close  of  the  grow- 


128  Principles  of  Plant  Culture. 

ing  period  tends,  therefore,  to  hasten  wood  maturity 
and  thus  to  reduce  damage  from  cold  (174).  Tillage 
should  be  early  discontinued  about  trees  liable  to  win- 
ter injury,  and  in  wet  seasons,  mulching  should  be  re- 
moved. Oats,  buckwheat  or  clover  sown  in  the  nursery 
or  orchard  in  late  summer  promotes  wood  maturity  by 
increasing  evaporation  from  the  soil  and  is  further 
useful  as  a  covering  to  the  ground  in  winter  (195). 
Draining  heavy  or  wet  soils  promotes  wood  maturity 
by  promptly  removing  surplus  water, 
b— By  treatment  of  the  plant. 

200.  Pinching    the   Terminal    Buds    (416  a)    a   few 
weeks  before  the  time  for  leaf  fall  favors  wood  matur- 
ity by  checking  growth,  as   does  the   removal  of  the 
younger  leaves,  in  which  food  preparation  is  most  ac- 
tive.    These   methods   may  be    employed  upon   young 
trees— especially  nursery  trees,  which  are  very  liable  to 
make  late  growth.     Early  gathering  of  the  fruit  from 
trees  of  late  varieties  also  tends  to  hasten  wood  maturity. 

201.  Protection     with     Non-Conducting     Materials 
prevents   damage  from  cold  in  many  herbaceous   and 
shrubby  plants  in   climates  where  they  are  not  fully 
hardy.     By  covering  such  plants  with  straw  or  other 
litter,  or  with  soil,  we   lessen  to  some  extent  the  in- 
tensity of  the  cold,  but — more  important — we  prevent 
frequent  freezing  and  thawing  (189  d),  and  in  a  meas- 
ure, the  heaving  of  the  ground,  which  on  heavy  or  wet 
soil  is  destructive  to  the  roots  of  plants.     A  covering  of 
straw,  leaves  or  other  litter  is  preferable  for  low,  her- 
baceous plants,  as  strawberries.     The  covering  should 
not  exceed  an  inch  or  two  in  thickness,  otherwise  the 


Injury  from  Cold  During  Growing  Period.      129 

plants  may  be  smothered  in  warm  winter  weather.  For 
taller  plants,  as  the  grape  and  raspberry,  the  soil  is 
usually  the  most  convenient  and  satisfactory  covering, 
as  a  litter  covering  tends  to  attract  mice,  that  often 
injure  woody  stems.  To  assist  in  bending  down  the 
stems,  a  little  earth  is  usually  removed  at  the  base  on 
the  side  toward  which  they  are  to  be  bent.  Shrubs  too 
large  for  bending  down  may  be  inclosed  in  straw  or 
similar  material. 

202.  A  Northerly  Exposure  is  generally  Least  Try- 
ing to  Plants  in  winter,  because  it  is  least  subject  to 
fluctuations  in  temperature.     The  influence  of  the  sun 
is  here  less  perceptible  and  snow  remains  longer  than 
upon  other  exposures.     The  summit  of  a  hill  is  usually 
less  trying  than  a  valley,  because  the  cold  air  tends  to 
seek  the  lower  places,  especially  in  still  weather  (209). 

203.  Wind-Breaks,  i.  e.,  plantings  of  trees  intended 
to  break  the  force  of  prevailing  winds,  act  beneficially 
in  lessening  damage  from  cold,  in  so  far  as  they  prevent 
snow  from  drifting  off  the  soil  and  mitigate  the  effects 
of  drying  winds  (189c). 

B  —  METHODS  OF  AVERTING  INJURY  FROM  COLD  DURING 
THE  GROWING  PERIOD. 

204.  Plants  are  much  more  susceptible  to  injury  from 
cold  during  their  growth  period  than  during  their  dor- 
mant period    (170).     Comparatively   few   plants,  how- 
ever, are  injured  by  cold  at  any  season  until  the  tem- 
perature falls  below  the  freezing  point  of  water  (32°  F., 
0°  C.),  or  when  so-called  hoarfrost  occurs.     It  is  this 


130  Principles  of  Plant  Culture. 

extreme  that  we  have  chiefly  to  fear  and  to  guard 
against  during  the  growing  period. 

205.  The  Cause  of  Hoarfrost.  A  sponge  saturated 
with  water  cannot  be  compressed  in  the  least  unless 
a  portion  of  the  water  escapes.  If  it  is  but  half  satu- 
rated, it  may  be  compressed  somewhat  without  any  es- 
cape of  the  liquid,  but  if  the  compression  passes  a  cer- 
tain limit,  the  water  will- begin  to  escape. 

The  air  is  like  a  sponge  in  being  capable  of  taking  up 
a  certain  amount  of  water.  But  the  amount  of  water 
the  air  can  take  up  depends  much  upon  its  temperature, 
its  capacity  for  water  increasing  as  the  temperature 
rises,  and  decreasing  as  it  falls. 

Suppose  a  given  amount  of  air  at  a  temperature  of 
50°  F.  has  taken  up  all  the  water  it  can  hold  at  that 
temperature.  It  is  clear  from  what  has  just  been  said, 
that  if  the  temperature  of  this  air  is  reduced,  some  of 
its  water  will  be  set  free  or  precipitated.  If  the  air 
were  only  half  saturated  at  50°  F.,  its  temperature 
could  be  reduced  considerably  before  any  of  its  water 
would  be  precipitated;  but  when  a  certain  degree  of 
cooling  is  reached,  the  air  will  no  longer  be  able  to  hold 
all  of  its  water,  and  a  part  will  be  precipitated.  The 
cooling  of  the  air  corresponds  to  the  compression  of  the 
sponge.  The  atmosphere  always  contains  more  or  less 
water  in  the  form  of  watery  vapor,  and  the  tempera- 
ture at  which  any  portion  of  the  atmosphere  on  cooling 
begins  to  precipitate  a  part  of  its  water,  is  called  the 
dew  point.  The  temperature  of  the  dew  point  depends, 
therefore,  upon  the  amount  of  water  the  air  contains. 


Injury  from  Cold  During  Growing  Period.      131 

When  the  dew  point  is  above  the  freezing  point  of  water 
(32°  F.,  0°  C.),  the  precipitation  is  in  the  form  of  dew 
or  rain;  but  when  it  is  below  the  freezing  point  of 
water,  the  precipitation  is  in  the  form  of  hoarfrost  or 
snow.  One  more  principle  needs  to  be  explained,  and 
we  are  ready  to  understand. 

206.  How   Frost  may  be   Foretold.     We  know  that 
sprinkling  the  floor  of  a  room  cools  the  air,  even  though 
the  water  used  is  no  cooler  than  the  air  of  the  room. 
This  is  because  the  air  in  taking  up  watery  vapor  ab- 
sorbs heat,   but  this  heat  is  set  free  again  when  the 
watery  vapor  is  precipitated.     A  steam  radiator  gives 
out  heat  because  the  steam  within  it  is  condensing  into 
water.     It  follows  that  when  the  dew  point  of  the  at- 
mosphere  is   reached,   a   very   considerable   amount   of 
latent  heat  is  given  off,  which  checks  the  fall  of  tem- 
perature.   The  temperature  of  still  air,  therefore,  rarely 
falls  much  below  the  dew  point,  and  since  the  latter  at 
any    given    temperature    depends    upon    the    amount 
of  the  moisture  in  the  air,  if  we  have  an  instrument- 
capable   of   indicating  both  the   temperature   and   the 
moisture  of  the  air,  we  may  compute  the  lowest  tem- 
perature to  which  the  atmosphere  will  be  likely  to  de- 
scend during  any  given  night,  and  thus  we  may  fore- 
tell frost  with  some  degree  of  certainty. 

207.  The     Sling     Psychrometer     (psy-chrom'-e-ter) 
enables  us  to  determine  both  the  temperature  and  the 
moisture  of  the  air.     This  instrument  consists  of  two  ac- 
curately-graduated thermometers   attached  to  a  board 
or  case    (Fig.    59).     The  bulb   of  one  thermometer  is 


132  Principles  of  Plant  Culture. 

inclosed  in  thin  muslin,  which  is  wet  just  before  using 
the  instrument  by  dipping  the  bulb  in  rain  water,  or 
is  connected  with  a  small  vessel  containg  rain  water, 
as  shown.  By  means  of  a  string  attached  to  the  board 
or  case  at  the  end  opposite  the  bulbs, 
the  instrument  is  whirled  about  in  the 
air  a  few  times,  after  which  the  ther- 
mometers are  quickly  read  and  the 
difference  in  the  readings  noted. 
When  the  air  is  comparatively  dry, 
evaporation  from  the  muslin  proceeds 
rapidly,  and  on  account  of  the  heat 
absorbed,  the  wet  bulb  indicates  a 
lower  temperature  than  the  dry  one. 
When  the  air  is  damp,  evaporation  is 
slower,  and  the  difference  between  the 
readings  of  the  two  thermometers  is 
less.  In  saturated  air,  evaporation 
ceases  and  the  two  thermometers  read 
alike.  By  means  of  the  following  table,  the  dew  point 
for  any  ordinary  out-door  temperature  and  atmospheric 
humidity  during  the  growing  season  may  be  readily 
determined. 

208.  To  Compute  the  Dew  Point.  Find  the  wet- 
bulb  depression  by  subtracting  the  wet-bulb  reading 
from  that  of  the  dry  bulb ;  locate  this  in  the  top  line  of 
the  table,  and  find  the  dry-bulb  reading  in  the  left  hand 
vertical  column.  Opposite  the  dry  bulb  reading,  in 
the  column  headed  with  the  number  indicating  the  wet- 
bulb  depression,  is  the  dew  point  sought. 


FIG.  60.  Sling  psy- 
chrometer,  used 
to  foretell  frost. 


Injury  from  Cold  During  Growing  Period.      133 


Example:    Dry-bulb  reading  .............  47° 

Wet-bulb  reading  ............  40° 

Wet-bulb  depression  .........  7° 

Table  for  Computing  the  Dew  Point  in  Degrees 

Fahrenheit. 


DRY 
BULB.              WET-BULB  DEPRESSION. 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

II 

12 

13 

36 

32 

30 

27 

24 

21 

18 

13 

+8 

—  1 

-12 

-32 

37 

34 

32 

29 

25 

21 

19 

15 

9 

+3 

—  7 

-23 

38 

35 

33 

30 

26 

23 

19 

17 

11 

-j-6 

—  3 

—16 

39 

36 

34 

31 

28 

24 

20 

16 

14 

8 

0 

-11 

-31 

40 

37 

35 

32 

29 

26 

22 

18 

12 

10 

+  3 

-  6 

—  22 

41 

39 

36 

33 

30 

27 

23 

19 

14 

8 

+  6 

-  2 

-15 

42 

40 

37 

34 

31 

28 

25 

21 

16 

10 

+  3 

-  2 

-  9 

-29 

43 

41 

38 

35 

33 

30 

26 

22 

18 

13 

+  6 

—  3 

-  5 

-20 

44 

42 

39 

37 

34 

31 

27 

24 

20 

15 

9 

-  1 

-12 

-13 

45 

43 

40 

38 

35 

32 

29 

25 

21 

17 

11 

+  4 

-  7 

-27 

46 

44 

41 

39 

36 

33 

30 

27 

23 

19 

14 

+  7 

-  2 

-18 

47 

45 

43 

40 

37 

35 

32 

28 

25 

21 

16 

10 

+  2 

-11 

48 

46 

44 

41 

39 

36 

33 

30 

26 

22 

18 

12 

+  5 

-  6 

49 

47 

45 

42 

40 

37 

34 

31 

28 

24 

20 

15 

+  8 

-  1 

50 

48 

46 

43 

41 

38 

36 

33 

29 

26 

22 

17 

11 

+  3 

51 

49 

47 

45 

42 

40 

37 

34 

31 

27 

23 

19 

13 

6 

52 

50 

48 

46 

43 

41 

38 

35 

32 

29 

25 

21 

16 

9 

53 

51 

49 

47 

44 

42 

40 

37 

34 

30 

27 

23 

18 

12 

54 

52 

50 

48 

46 

43 

41- 

38 

35 

32 

28 

24 

20 

15 

55 

53 

51 

49 

47 

45 

42 

39 

36 

33 

30 

26 

22 

17 

56 

54 

52 

50 

48 

46 

43 

41 

38 

35 

32 

28 

24 

19 

57 

55 

53 

51 

49 

47 

45 

42 

39 

36 

33 

30 

26 

22 

58 

56 

54 

52 

50 

48 

46 

43 

41 

38 

35 

31 

28 

24 

59 

57 

55 

53 

51 

49 

47 

45 

42 

39 

36 

33 

29 

26 

60 

58 

56 

54 

52 

50 

48 

46 

43 

41 

38 

35 

31 

28 

6  1 

59 

57 

56 

54 

52 

49 

47 

45 

42 

39 

36 

33 

29 

62 

60 

58 

57 

55 

53 

51 

48 

46 

43 

41 

38 

35 

31 

Opposite  47°,  in  the  left  hand  column,  and  under  7 
in  the  top  line,  we  find  28° — the  dew  point.  If  these 
readings  are  obtained  toward  sunset  on  a  clear,  still 
evening,  we  should  expect  frost,  because  the  dew  point 


134  Principles  of  Plant  Culture. 

is  4°  below  the  freezing  point  of  water.  A  slight 
wind,  a  hazy  atmosphere,  or  a  few  fleecy  clouds  would 
render  frost  doubtful.  With  a  dry-bulb  reading  of  45° 
and  a  dew  point  of  25°,  a  killing  frost  might  be  ex- 
pected. 

209.  Cold   Air    Drainage.     Warm   air,  being  lighter 
than  cold  air,  tends  to  rise,  while  the  colder  air  tends  to 
fall.     In  a  still  atmosphere,  therefore,  the  cold  air  accu- 
mulates in  the  lowest  places.    This  explains  the  familiar 
fact  that  hollows  and  valleys  are  colder  in  still  weather 
than  ridges  and  mountains.     In  a  falling  temperature 
and  in  the  absence  of  wind,  gentle  currents  of  the  colder 
air  tend  to  follow  the  water  courses,  which  explains  in 
part  why  frost  so  often  "goes  in  streaks." 

210.  Wind  Tends  to  Avert  Frost  because  it  prevents 
the  settling  of  the  colder  air  and  thus  keeps  the  tem- 
perature of  the  lower  strata  of  the  atmosphere  nearly 
uniform. 

211.  Clouds,  Haze  and  Smoke  Tend  to  Avert  Frost 
because  they  act  to  some  extent  like  a  blanket  in  pre- 
venting the  radiation  of  heat  from  the  earth,  and  thus 
check  the  fall  in  temperature   (216). 

212.  The    Proximity   of   a    Body    of   Water   Tends 
to  Avert  Frost  because  the  water  cools  slower  than  the 
air  and  thus  checks  the  fall  in  temperature  of  the  at- 
mosphere  in  the  vicinity;   also   because  it  keeps    the 
neighboring  atmosphere  moist,  thereby  raising  the  tem- 
perature of  its   dew  point    (205).     The  proximity   of 
buildings  and  trees  tends  to  avert  frost,  probably  be- 
cause these  objects  give  up  their  heat  gradually  and 
thus  temper  the  surrounding  atmosphere. 


Injury  from  Cold  During  Growing  Period.      135 

213.  The    Localities    Most    Subject    to    Untimely 
Frosts   are   narrow   and   deep   valleys  inclosed  on  all 
sides,    and    inclined   valleys    that    serve    as    channels 
through  which  cold  air  flows  to  lower  levels.     Partially- 
cleared  districts  usually  suffer  more  from  frosts  than 
these  fully  cleared,  because  the  remaining  forests  ob- 
struct air  drainage. 

Marsh  areas  are  subject  to  frost,  because,  in  addition 
to  their  low  situation  as  compared  with  the  surrounding 
land,  their  luxuriant  vegetation  tends  to  cool  the  at- 
mosphere in  the  vicinity  by  exposing  a  large  radiating 
surface  and  promoting  abundant  evaporation. 

Valleys  surrounding  elevated  lakes  that  have  an  out- 
let through  which  the  colder  air  may  flow  to  lower  re- 
gions are  particularly  free  from  damaging  frosts.  The 
valley  of  Keuka  Lake,  in  west-central  New  York,  so 
famous  for  its  vineyards,  is  of  this  class. 

214.  Thermal    Belts.     In  some  elevated  districts  of 
mountainous  regions,  localities  of  greater  or  less  extent 
are  found  in  which  damaging  frosts  are  almost  unknown. 
These  have  been  called  thermal  belts,  and  their  freedom 
from  frost  is  explained  by  the  merging  of  the  warm  air, 
that  rises  somewhat  rarified  by  heat  from  the  lower  val- 
leys, with  the  atmosphere  of  the  more  elevated  region 
that  is  rarified  to  an  equal  extent  by  the  high  altitude. 
Thus  the  warm  air  ceases  to  rise,  but  lends  its  heat  to 
temper  the  climate  of  the  adjacent  mountains. 

215.  Liability    to    Damaging    Frost    Depends    Com- 
paratively Little  upon  Latitude.     Within  the  tropics 
are  areas  where  frost  is  unknown  because  the  temper- 


136  Principles  of  Plant  Culture. 

ature  never  falls  to  the  freezing  point.  But  in  local- 
ities subject  to  frost,  the  liability  of  damage  to  vegeta- 
tion from  this  cause  is  goverened  more  by  cold  air 
drainage  (209)  and  proximity  to  water  than  by  latitude. 
It  is  as  important  to  select  locations  for  peach  growing 
with  reference  to  spring  frosts  in  the  Carolinas  as  in 
the  peach  belt  of  Michigan,  and  favorable  locations  for 
the  apple  in  Wisconsin  sometimes  escape  damage  from 
spring  frosts  in  seasons  when  the  apple  crop  is  cut  off 
by  frost  from  extensive  regions  of  the  southern  states. 

216.  Methods  of  Preventing  Injury  by  Frost.  Any 
non-conducting  material  lying  between  the  earth  and 
space,  whether  spread  directly  upon  the  earth  or  at  a 
considerable  height  above  it,  acts  as  a  blanket  to  inter- 
cept the  radiating  heat,  and  thus  prevents  in  a  measure 
the  coding  of  objects  beneath  it.  For  this  reason, 
straw,  muslin  or  other  non-conducting  material  spread 
over  plants,  usually  protects  them  from  frost. 

While  it  is  easy  to  protect  a  few  plants  from  frost 
by  covering  them  directly,  it  is  much  more  difficult  to 
protect  large  plantations  in  this  manner.  Considerable 
plantings  of  the  strawberry  have  been  successfully  pro- 
tected from  frost  by  covering  the  rows  in  the  evening 
with  straw  or  marsh  hay,  and  where  these  materials 
are  convenient,  the  work  may  often  be  cheaply  and 
quickly  performed. 

Attempts  to  prevent  frost  on  a  large  scale  by  the 
heat  of  fires  or  by  burning  material  that  produces  much 
smoke  or  vapor,  have  not  been  sufficiently  successful  to 
commend  these  methods  for  general  application. 


Plants  as  Affected  by  Excessive  Water.        137 

SECTION  III.     THE  PLANT  AS  AFFECTED  BY  UNFAVOR- 
ABLE WATER  SUPPLY. 

A  — BY  EXCESSIVE  WATER. 

217.  Excessive  Water  in  the  Soil  Destroys  the 
Roots  of  plants.  We  saw  that  oxygen  is  necessary  to 
the  life  of  roots  (89).  When  the  soil  cavaties  are 
filled  with  water,  the  roots  are  soon  deprived  of  oxygen, 
because  the  little  oxygen  contained  in  the  water  is  soon 
exhausted  (93).  Smothering  and  decay  of  the  roots 
follow.  Seeds  planted  under  such  conditions  usually 
fail.  The  soil  water  that  is  most  useful  to  land  plants 
is  that  which  remains  attached  to  the  earthy  particles 
after  percolation  has  nearly  ceased  (capillary  water). 
Such  water  is  well  aerated  because  it  is  interspersed 
with  cavities  that  are  filled  with  air  (91). 

In  the  open  ground,  the  remedy  for  excessive  soil 
water  may  usually  be  found  in  underground  drainage. 
But  the  same  trouble  often  occurs  in  potted  plants,  as 
the  result  of  too  compact  soil  or  too  copious  watering. 
The  expert  recognizes  this  condition  by  a  sour  odor  of 
the  soil,  by  lifting  the  pot,  or  by  tapping  the  pot  with 
his  knuckle.  If  the  soil  is  soggy,  the  weight  will  betray 
the  fact,  or  the  sound  given  out  by  the  pot  will  be  that 
of  a  compact  mass  instead  of  a  more  or  less  hollow 
body,  as  is  the  case  with  a  pot  of  well-aerated  soil.  To 
remedy  the  evil,  repot  the  plant  in  fresh  soil  of  a 
proper  condition  of  moisture,  providing  abundant 
drainage  at  the  bottom  of  the  pot  (412). 

seta    10 


138  Principles  of  Plant  Culture. 

218.  Injudicious     Watering    is    perhaps    the    most 
common    cause    of   failure    in    growing   potted   plants. 
The  amateur  to  often  assumes  that  the  chief  need  of 
the  plants  is  frequent  watering,  and  so  gives  water  in 
spoonful  doses  as  the  surface  soil  of  the  pot  appears 
dry,  without  observing  the   state   of  the  soil  beneath. 
The  roots  of  the  plants  in  the  meantime  may  be  smother- 
ing in  water-logged  soil  or  starving  from  drought.     If, 
owing  to  inexperience,  the   condition   of  the  soil  can- 
not be  determined  by  the  means  above  noted,  the  soil 
may  be  tipped  out  upon  the  hand  without  materially 
disturbing  the  roots  of  the  plant,  by  reversing  the  pot 
and  gently  striking  its  rim  on  the  edge  of  the  bench  or 
table.     The    real    condition    can    then    be    readily    de- 
termined. 

219.  Copious  Waterings  at  Considerable  Intervals 
are  Preferable  to  frequent  slight  waterings.     It  should 
never  be  forgotten  that  air  is  as  essential  as  water  to 
the  well-being  of  roots  (89),  and  that  the  soil,  however 
porous,   requires   occasional   ventilation    (93).     A   con- 
siderable quantity  of  water  poured  upon  the  surface 
soil  of  a  potted  plant,  in  passing  downward  not  only 
thoroughly  moistens  the  soil  particles,  but  acts  like  a 
piston,  forcing  the  vitiated  air  of  the  soil  cavities  ahead 
of  it  and  out  through  the  drainage  hole  at  the  botom  of 
the  pot,  while  fresh  air  enters  from  above  as  the  sur- 
plus water  passes  out  beneath.     Manure  water  should 
not  often  be  used,   as  there   is   danger  in   giving  the 
plant  too  much  food. 

220.  Rapidly-Growing    Plants  Require  More    Water 
and  are  less  liable  to  suffer  from  over-watering  than 


Plants  as  Affected  by  Excessive  Water.        139 

slower-growing   ones.     During   the   rest   period    (172), 
plants  should  be  given  very  little  water. 

221.  Some     Species     Require     More    Water    than 
Others.     The  native  habitat  of  the  plant  is  a  partial 
guide  to  the  amount  of  water  needed.     Plants  native 
to  arid  regions,   as  the  cacti   and  those  from  treeless, 
rocky   locations,   require   little   water    and   are   readily 
destroyed    by    over    watering.     "Plants    with    narrow 
and   tough    leaves,    especially   when   the    leaf-blade    is 
vertically  placed,  do  not,  as  a  rule,  like  much  water; 
plants    with    broad,    leathery    leaves    prefer    a    damp 
atmosphere  to  great  moisture  at  the  roots.     Succulent 
plants  with  hard  epidermal  cells   (leafless  Euphorbias, 
succulent   Composites,   Aloes   and   Agaves),    and  thin- 
leaved  plants  with  a  strong  wooly  covering  of  hairs  are 
further   examples   of  plants  which   require  very  little 
water. '  '* 

222.  Excessive     Watering    sometimes    Produces     a 
Dropsical  Condition    (osdema)   in  the  leaves  of  plants 
under  glass.     This  is  most  likely  to  occur  in  winter, 
when  sunlight  is  deficient,  especially  if  the  soil  is  kept 
nearly  or  quite  as  warm  as  the  air.     Water  accumulates 
in  the  cells,  abnormally  distending  their  walls— some- 
times even  to  bursting.     An  unnatural  curling  of  the 
leaves,  with  yellow  spots   and   small  wart-like   excres- 
cences on  their  surfaces,  are  some  of  the  symptoms  of 
this  trouble.     Less  water,  increased  light  and  reduced 
bottom  heat  (362  a)   furnish  the  remedy. 

Frenching,  a  disease  that  often  attacks  growing  to- 
bacco on  excessively-wet  clay  soils,  may  be  caused  by 

*  Sorauer,   Physiology   of  Plants,   p.   207. 


140  Principles  of  Plant  Culture. 

undue  absorption  of  water  by  the  roots.  The  leaves 
of  affected  plants  grow  narrow,  and  are  thick,  fleshy 
and  wrinkled.  If  the  plants  are  pulled  sufficiently  to 
break  the  tap-root,  before  the  disease  has  progressed  too 
far,  they  often  recover. 

223.  Water-Sprouts      (sap-sprouts,     gormands)      on 
fruit  trees  are  sometimes  due  to  an  excess  of  water  in 
the  soil.     These  thick,  rapidly-growing  shoots,  with  re- 
mote leaves  and  poorly-developed  buds,  growing  from 
the  main  branches  of  unthrifty  fruit  trees,   are  most 
common  on  undrained,  heavy  soils.     They  rarely  pro- 
duce much  fruit,  but  tend  to  rob  the  bearing  branches 
of  light   and  nourishment.     They  usually  continue  to 
grow  late,  and  in  severe  winters  are  often  injured  by 
cold.     Water-sprouts  may  also  result  from  over-prun- 
ing and  from  injury  of  the  tree  by  cold,  but  in  the  ab- 
sence   of    these    conditions   they   suggest   the   need   of 
drainage. 

224.  Fruits  and  Vegetables   often  Crack  from   Ex- 
cessive Moisture,  either  through  tco  much  absorption 
by  the  roots  or  by  direct  absorption  through  the  skin. 
Cracking  is  most  frequent  after  heavy  rains  following 
drought.     Apples,  tomatoes,  melons,  carrots,  kohl-rabi, 
cabbage  and  potato  tubers,  are  subject  to  it.     On  wet 
soils,  drainage  may  largely  remedy  the  evil.     The  se- 
lection  of   varieties   least   subject  to  cracking   is    also 
helpful,  especially  in  melons  and  tomatoes  which  often 
crack  in  comparatively   dry  weather.     In  these   cases, 
the  cracking  is  probably  due  to  an  unequal  maturing 
of  the  fruit  which  causes  certain  parts  to  grow  faster 
than  others.     The  bursting  of  cabbage  heads  is  due  to 


Plants  as  Affected  by  Excessive  Water.        141 

the  excessive  absorption  of  water  by  the  roots.  To  pre- 
vent it,  we  start  the  plants  by  pulling  on  the  stem  suffi- 
ciently to  break  a  part  of  the  roots. 

225.  Knobby   Potatoes  are  caused  by  a  wet  period 
following  a  drought  during  the  ripening  season.     Parts 
of  the  plant  that  are  still  alive,  stimulated  by  abundant 
water,  resume  growth.     But  since  cell  division  is  possi- 
ble only  in  the  parts  containing  protoplasm,  the  ma- 
ture   cells  of  the   tuber  can  no   longer   divide,   hence 
growth  is  limited  to  the  younger  parts,  i.  e.,  the  vicinity 
of  the  buds   (eyes),  and  these  therefore  grow  out  into 
unshapely   protuberances.     The  knob  consumes   a  part 
of  the  starch  previously  stored  in  the  tuber  from  which 
it  grows,   hence  knobby   potatoes   are   poorer   in    food 
value  than  smooth  ones  of  the  same  lot. 

Certain  varieties  of  potato  are  more  disposed  to 
knobbiness  than  others.  In  varieties  normally  free  from 
it,  the  planting  of  knobby  seed  tubers  probably  does  not 
tend  to  increase  the  inclination  to  knobbiness. 

226.  Excessive  Moisture  in  the  Air  is  Injurious  to 
plants,  since  it  tends  to  hinder  normal  transpiration 
(74)    and  favors  the  growth  of  certain  fungous  para- 
sites (321).     In  the  greenhouse,  we  control  the  atmos- 
pheric moisture  by  ventilation  and  care  in  the  use  of 
water.     Out  of  doors,  we  guard  against  excessive  moist- 
ure in  the  air  by  giving  plants  sufficient  rcom  to  favor 
the  circulation  of  air  between  them.     The  latter  precau- 
tion  is   important   in   orchard   planting,   since   several 
fungi  that  prey  upon  fruit  trees,  as  the  apple  scab  (328) 
and  pear  blight  (323),  flourish  in  a  damp  atmosphere. 


142  Principles  of  Plant  Culture. 

B  — THE  PL.ANT  AS  AFFECTED  BY  INSUFFICIENT  WATER. 

227.  Insufficient   Moisture  in  the   Air   Causes  Ex- 
cessive Transpiration   (74),  which  reduces  the  tension 
of  the  cell-walls  and  thus  retards  growth  (62).     It  also 
tends  to  clog  the  leaves  with  useless  mineral  matters, 
causing  their  premature  death    (125),  and  favors  the 
development  of  certain  fungous  parasites.     The  effects 
of  insufficient  moisture  in  the  air  are  often  very  notice- 
able upon  plants  kept  in  living-rooms  in  winter.     Such 
plants,  especially  when  few  in  number,  rarely  make  sat- 
isfactory growth  and  the  lower  leaves  continually  per- 
ish.    Moistening  the  air  by  evaporating  water  in  the 
room,  or  setting  the  pots  containing  the  plants  upon  a 
table    covered  with   moist    sand   usually  remedies   the 
trouble. 

Insufficient  moisture  in  the  open  air  rarely  occurs 
unless  there  is  also  a  dearth  of  water  in  the  soil. 

228.  Insufficient    Moisture    in    the    Soil    Retards 
Growth  both  by  reducing  the  tension  of  the  cell-walls 
(62),  and  by  lessening  the  supply  of  food  from  the  soil. 
The  tendency  of   drought   is,  therefore,  to  starve  the 
plant. 

Plants  that  have  been  subject  to  insufficient  water 
from  the  beginning  usually  suffer  less  from  drought 
than  those  previously  well  watered,  because  their  root 
system  has  become  more  extensively  developed  (111). 

229.  Drought  tends  to  Hasten  Maturity,  especially 
in  annual  plants,  since  it  favors  flowering  (134).     Let- 
tuce, spinach,  rhubarb,  etc.,  "run  to  seed"  earlier  if 
insufficiently   supplied    with    water.      Potatoes    usually 


Plants  as  Affected  l>y  Insufficient  Water.        143 

ripen  earlier  in  dry  seasons  than  in  wet  ones.  If  the 
drought  is  sufficiently  severe  or  sufficiently  prolonged, 
diminution  or  failure  of  seedage  results. 

230.  Toughness    of    Plant    Tissues     Results    from 
Drought.     The  crispness  and  tenderness  that  give  qual- 
ity to  salad  vegetables,  as  celery,  lettuce,  radish,  etc., 
due   to    a    distended    condition    of    their    cell-walls,    is 
largely  wanting  when  the  water  supply  during  growth 
has  been  insufficient. 

Insufficient  water  during  growth  injures  the  quality 
of  tobacco.  Leaves  thus  affected  have  a  peculiar  spot- 
ted appearance  when  cured,  and  do  not  "sweat" 
properly. 

231.  Crumbling    of   the   Surface    Soil    (cultivation) 
tends  to  Prevent  Drought,  since  it  'greatly  lessens  the 
points  of  contact  in  the  soil  particles,  and  thus  inter- 
feres with  the  rise  of  the  soil  water  by  capillary  attrac- 
tion to  the  surface  where  evaporation  chiefly  occurs. 
An  air-dry  surface  layer  of  crumbled  soil  also  tends  to 
prevent  evaporation  by  keeping  the  soil  cooler  beneath. 
A  puddled  crust  on  the  surface  of  the  soil,  as  is  formed 
by  rain  on  soils  containing  clay,  tends,  on  the  other 
hand,  to  restore  capillary  action  and  thus  to  promote 
evaporation.    Some  gardeners  cultivate  their  hoed  crops 
as  soon  as  possible  after  rains  for  the  main  purpose  of 
breaking   this    crust   and   thus    stopping   the   capillary 
action. 

Cultivation  is  also  beneficial  by  aerating  the  soil  (93). 
The  roots  of  plants  should  never  be   forgotten  nor 
ignored  in  cultivating  crops    (109). 


144  Principles  of  Plant  Culture. 

232.  Mulching  tends  to  Prevent  Drought  by  inter- 
posing a  layer  of  poor-conducting  material  between  the 
ground  and  the  sun's  rays.     This  keeps  the  surface  soil 
cooler  and  so  checks  evaporation. 

The  best  mulching  material  is  the  one  that  conducts 
both  heat  and  moisture  slowest.  Straw,  marsh  hay, 
leaves,  manure,  shavings,  sawdust,  spent  tan  and  sand 
are  all  useful  for  mulching,  but  the  first  four  named 
are  generally  preferable  to  the  others,  especially  if  free 
from  weed  seeds. 

Growing  plants  tend  to  dry  the  soil  because  the  root- 
hairs  continually  draw  in  soil  water  and  force  it  into 
the  leaves  (101)  where  it  passes  off  by  transpiration 
(74).  Weeds,  therefore,  rob  crops  of  moisture  (336). 

233.  Irrigation,  i.  e.,  the  extensive  watering  of  out- 
door plants,  is  the  final  remedy  for  drought.     It  is  nec- 
essary to   plant  culture  in   arid  regions,  and  may  be 
profitably  employed  at  certain  times  in  the  great  ma- 
jority of  seasons  in  many  localities  where  the  annual 
rainfall  would  satisfy  the  needs  of  crops,  were  it  more 
uniformly  distributed. 

234.  Drying  beyond  a  certain  limit  Kills  Plant  Tis- 
sues by  destroying  in  part  their  power  for  conducting 
water.     Care  should  be  used  to  retain  the  normal  moist- 
ure in  buds  (394),  cuttings  (358),  and  cions  (386)  and 
in  the  roots  of  plants  lifted  for  transplanting. 


Plants  as  Affected  by  Excessive  Light.          145 

SECTION   IV.     PLANTS   AS  AFFECTED  BY  UNFAVORABLE 
LIGHT. 

A  —  BY  EXCESSIVE  LIGHT. 


235-  The  Unobstructed  Rays  of  the  Sun  are  often 
Injurious  to  young  seedlings,  to  unrooted  cuttings  and 
to  plants  recently 
transplanted.  It  is  dif- 
ficult to  separate  the 
influences  of  light  and 
heat,  since  the  heat  is 
usually  greatest  where 
the  sun's  rays  are 
brightest ;  but  bright 
light  probably  stimu- 
lates transpiration  (74)  FIG.  61.  Lath  screen  used  for  shad- 
v  '  ing  cold-frames  and  tender  plants  in 

independent  of  heat  the  open  ST°U^-  (A«er  Bailey.) 
and  thus  tends  to  exhaust  the  plant  of  water.  Various 
devices  are  used  to  break  the  force  of  the  solar  rays. 
In  out-door  culture,  screens  of  lath  (Figs.  61,  62), 
cloth  or  brush  (Fig.  63)  are  often  placed  over  beds  con- 
taining cuttings  or  ten- 
der seedlings,  as  of 
many  con  e-b  earing 
trees.  Cuttings  in  the 
nursery  may  be  shaded 

FIG.  62.  Shed  screen  built  of  three-  hv  ennnnrtino-  a  hnarrl 
inch-wide  slats,  for  shading  tender  ^  Supporting  a  DOarc 
plants  and  for  storing  pots  and  nvpr  fUp  rnw  nri  cVmrt 
boxes  of  slow-germinating  seeds.  OVer  tne  row>  °n  S 

stakes    (Fig.  64),  so  as 
to  protect  them  during  the  warmer  hours  of  the  day. 


146  Principles  of  Plant  Culture. 

Shingles,  flower-pots  or  large  green  leaves,  as  of  the 
burdock,  are  useful  for  shading  plants  of  the  cabbage, 
tomato,  etc. 

In    culture    under    glass,    the    glass    is    often    thinly 
washed  with  lime  or  clay  to  render  it  partially  opaque, 


FIG. 
ground. 


Brush  screen,    for  shading   tender  plants  in  the   open 
(After    Bailey.) 


or  lath  screens  are  used  either  above  or  below  the  glass. 
On  greenhouse  benches,  sheets  of  thin  paper  or  light 
cloth  screens  are  useful  for  shading  cuttings,  recently- 
planted  seedlings  and  germinating  seeds. 

Shading  should  never  be  so  put  on  as  to  prevent  a 
free  circulation  of  air  about  the  plants. 


FIG.  64.  Board  shade  for  recently-set  plants,  or  for  cuttings 
not  yet  rooted. 

A  shade  that  obstructs'  only  a  part  of  the  rays  of  sun- 
light at  a  time,  as  does  the  lath  or  brush  screen,  is 
generally  preferable  to  one  that  continuously  breaks 
the  force  of  all  the  rays,  as  does  paper  or  whitewashed 


236.  Cauliflower  Heads  should  be  Sheltered  from 
Sunlight  to  prevent  the  formation  of  chlorophyll  in 
their  cells  (59),  which  darkens  their  color  and  gives 


Plants  as  Affected  by  Insufficient  Light.        147 

them  a  strong  flavor.  The  leaves  surrounding  the 
head  may  be  tied  about  it  or  broken  over  so  as  to  shade 
it  from  direct  sunlight.  Burst  cabbage  heads  should 
be  cut  at  once  to  avoid  the  formation  of  chlorophyll 
within  them. 

B  — PLANTS  AS  AFFECTED  BY  INSUFFICIENT  LIGHT. 

237.  Insufficient  Light  is  a  Frequent  Cause  of 
Abnormal  Development  in  plants.  Some  of  its  effects 
are 

a — Excessive  elongation  of  the  cells  of  the  internodes 
(75),  causing  the  plants  to  "draw  up"  or  grow  spin- 
dling. 

b — Deficient  formation  of  chlorophyll  (59),  giving 
the  foliage  a  pale-green,  yellowish  or  whitish  tint,  and 
resulting  in 

c — Lessened  food  formation,  causing  reduced  leaf  de- 
velopment and  deficient  vascular  bundles  (67). 

d — Reduced  transpiration  tending  to  watery,  weak- 
celled  growth. 

e — Weakening  of  the  color  and  flavor  of  some  fruits, 
as 'the  apple  and  strawberry. 

f— Preventing  pollination   (150). 

g — Reducing  fruitfulness. 

Owing  to  these  causes,  plants  grown  in  deficient  light 
have  tall,  slender,  weak  stems,  few,  small,  pale  leaves 
and  scanty  roots  and  are  often  unfruitful.*  Such  plants, 
though  of  species  that  normally  grow  upright,  are 
often  unable  to  stand  erect  without  support.  Familiar 


*  Tomato  plants  grown  in  winter  on  poorly-lighted  benches  are 
often  unfruitful   even   when    they   grow  well  and  bloom   freely. 


148  Principles  of  Plant  Culture. 

examples  are  cabbage  and  tomato  plants  that  lop  over 
when  planted  out,  because  grown  in  the  seed- box  to 
transplanting  size  without  "pricking  off"  (105)  ;  and 
grain  sown  too  thickly  on  rich  ground,  that  falls 
(lodges)  before  maturity. 

238.  Too    Close    Planting    Causes    Deficient   Light 
and    all   the   resulting    evils.     Indian   corn   grown   too 
thickly  does  not  ear  well  and  is  lacking  in  nutritive 
qualities;  strawberry  plants  grown  too  closely  do  not 
fruit   well   and   the    fruit   lacks   flavor    and  firmness; 
nursery  trees   grown  too   closely  are  slender-stemmed, 
deficient  in  foliage  and  have  poorly  developed  roots. 
A  rule  to    govern  distance    in  planting    has    already 
been  given  (122). 

When  a  slender  and  flexible  growth  is  desired,  as  in 
trees  grown  for  hoop  poles,  or  willows  for  wicker-work 
and  tying,  a  certain  amount  of  crowding  is  advisable. 

239.  Weeds  Cause  Deficient   Light  in  low-growing 
crops  as  strawberries,  dwarf  beans,  potatoes,  etc.,  and 
also  tend  to  rob  the  plants  of  food  and  moisture.   They 
are,  therefore,  decidedly  injurious  (336). 

240.  Plants  Under   Glass  are  Especially    Liable  to 
Suffer   from   Deficient   Light,  because  the  walls  and 
sash  bars  of  the  structure  necessarily  intercept  a  con- 
siderable part  of  the  solar  rays.     The  roofs  of  glass 
houses  should  be  formed  of  large  lights  of  glass,  with 
the  smallest  possible  sash  bars,  and  the  benches  should 
be  arranged  to  bring  the  plants  as  near  to  the  glass  as 


Plants  having  their  leaves  densely  covered  with  hairs 
generally  require  a  large  amount  of  light. 


Plants  as  Affected  by  Insufficient  Light.        149 

241.  The  Electric  Light  has  been  found  useful  as  a 
supplement  to  the  scanty  sunlight  of  short,  early-winter 
days,    in   forcing    certain   vegetables 
and  flowers. 

242.  Insufficient     Pruning      Pre- 
vents the   formation  of   Fruit-Buds 
in  orchard  trees  by  restricting  light 
and    thus    reducing   food    formation 
(58).       Compare     Fig.     65,     which 
shows   a   fruit   branch  of  the  apple 
tree   grown  where  exposed  to  abun- 
dant sunlight,  with  Fig.  66,  showing 
one  grown  in  partial  shade.* 

243.  Blanching    of    certain    vege- 
tables as  celery,  endive,  cardoon  and 
sea  kale  is  practiced  by  gardeners  to 
render  them  more  tender   and  deli- 
cate.    It  is  effected  by  excluding  the 
light  from  the  parts  desired  for  use, 
until    the    chlorophyll    (57)     mostly 
disappears,    by    banking    the    plants 

FIG.  65.  Fruit  branch  with  earth  or  inclosing  them  in  paper 

of     apple     grown      in 

*^S»w    A^O  t  h  e  r  or  in  drain-tile.     Very  close  planting 

grown     'in        partial^     SQmetimes     practiced     to     promote 

F,      fruit-buds;      L, 
lea^-buds.        (After  blanching. 


FIG.  65.         FIG.  66. 


*  See    Bulletin    No.    37,    Rhode    Island    Agricultural    Experiment 
Station. 


150  Principles  of  Plant  Culture. 

SECTION    V.     PLANTS    AS    AFFECTED    BY    UNFAVORABLE 
WIND. 

A— BY  EXCESSIVE  WIND. 

244.  Damage  to  trees  and  other  plants  by  excessive 
wind  is  too  familiar  to  need  notice,  except  to  suggest 
preventive  measures. 

a — The  premature  blowing  off  of  fruits  may  be  in  a 
measure  prevented  by  planting  fruit  trees  where  they 
are  more  or  less  sheltered  from  prevailing  winds  by 
shade  trees,  buildings,  forests  or  elevations  of  land. 
Orchards  may  be  in  part  protected  by  planting  a  wind- 
break on  the  windward  side  (203). 
.  b— Shade  trees  in  exposed  situations  should  be 
headed  low,  and  the  head  should  be  formed  of  numerous 
branches.  The  higher  the  head,  the  more  it  is  exposed 
to  wind  and  the  greater  is  the  leverage  upon  the  trunk. 
Several  small  branches  are  better  able  to  bear  the 
tempest  than  a  few  larger  ones. 

Shade  trees  for  exposed  situations  should  be  of  species 
not  likely  to  be  deformed  by  wind.  Certain  trees,  as  the 
white  maple,*  often  develop  one-sided  if  planted  where 
exposed  to  prevailing  winds,  while  others,  as  the  sugar 
maplef  and  Norway  maplej  are  not  thus  affected. 

B— PLANTS  AS  AFFECTED  BY  INSUFFICIEBT  WIND. 

245.  Insufficient  Wind   Promotes  the   development 
of  certain  Fungus  Parasites  (321)  by  favoring  an  ex- 

*  Acer  dasycarpum.          f  Acer  saccharinum.          %  Acer  platanoides. 


Plants  as  Affected  by  Excessive  Food.          151 

cessively  moist  atmosphere.  Orchards  too  closely 
planted  or  surrounded  by  wind  barriers  suffer  more 
from  fungous  attacks,  than  those  having  freer  circula- 
tion of  air  between  the  trees. 

246.  Insufficient     Wind     Promotes     Damage  from 
Frost   by   permitting  cold   air  to  settle   in   the   lower 
places    (209).     On  these   accounts,    gardens   and   fruit 
plantations  should  not  be  entirely  surrounded  by  wind 
barriers. 

247.  Pollination  (150)  is  Dependent  upon  Wind  in 
many  plants,  as  the  coniferous  trees,  oaks,  elms,  birches 
and  sedges;  but  as  the  pollen  of  such  plants  is  very 
light,  their  fruitfulness  is  not  often  much  restricted  by 
insufficient  wind. 

SECTION    VI.     PLANTS   AS   AFFECTED   BY  UNFAVORABLE 
FOOD  SUPPLY. 

We  saw  that  water  is  the  most  important  constituent 
of  plant  food  (62)  and  we  have  already  considered  the 
plant  as  affected  by  water  supply  (Section  III).  But 
a  proper  supply  of  the  other  essential  food  constituents 
is  only  second  in  importance  to  that  of  water. 

i 
A  — PLANTS  AS  AFFECTED  BY  EXCESSIVE  FOOD. 

248.  Excessive  food  is  not  the  extreme  that  we  have 
most  to  fear,  since  natural  soils  are  rarely  excessively 
fertile,  and  we  can  only  make  them  so  by  costly  meth- 
ods.    Indeeed,  nearly  all  the  constituents  of  plant  food 
may  be  present  in  excess  of  plants'  requirements  with- 


152  Principles  of  Plant  Culture. 

out  working  harm.  Nitrogen,  however,  which  aside 
from  water  is  the  most  potent  food  constituent,  must 
be  used  with  some  discretion. 

249.  Excessive  Nitrogen  Stimulates  Growth  at  the 
expense  of  flowers,  seed  and  fruit.     In  crops  grown  for 
these  parts,  therefore,  fertilizers  rich  in  nitrogen  must 
be  used  with  caution.     Apple,  pear  and  quince  orch- 
ards liberally  manured  with  such  fertilizers  produce  an 
excessive,  over-succulent  growth  of  wood,  that  is  sub- 
ject to  blight  and  winter  injury  and  forms  compara- 
tively few  fruit  buds.     Grain  under  similar  conditions 
forms    long,    weak    straw,    with     poorly-filled    heads. 
Grape  vines  on  over  manured  ground  produce  excessive 
wood  with  few  and  late-ripening  bunches. 

There  is  little  danger  of  over-manuring,  however, 
with  crops  grown  for  parts  other  than  flowers,  fruit  or 
seed,  so  long  as  decomposed  stable  manure  is  used 
(251).  But  the  more  concentrated  animal  manures,  as 
those  from  poultry  and  the  hog,  the  chemical  com- 
pounds of  nitrogen,  as  nitrate  of  soda  and  sulfate  of 
ammonia  (261),  and  the  so-called  "high-grade"  com- 
mercial fertilizers  must  be  used  with  caution,  as  they 
may  destroy  the  plants  if  applied  in  excess. 

B  — PLANTS  AS  AFFECTED  BY  INSUFFICIENT  FOOD. 

250.  It  is  difficult  to  separate  the  effects  of  a  lack  of 
food  from  those  of  a  lack  of  water,  since  the  food  is 
mainly  conveyed  to  the  plant  in  the  soil  water   (62). 
But  even  with  a  proper  water  supply,  if  one  or  more 


Plants  as  Affected  by  Insufficient  Food.        153 

of  the  required  food  materials  is  lacking  (60),  a  nor- 
mal plant  structure  cannot  be  built  up.  An  excess  of 
one  food  substance  cannot  compensate  for  the  lack  of 
another,  except  in  a  few  instances. 

251.  Insufficient  Food  Dwarfs  the  Plant  in  all  its 
parts.     A  dwarfing  of  the  size  of  the  plant  body  may 
occur,  however,   without   a  corresponding   dwarfing  of 
the  seed  product;  hence  plants  may  often  bear  their 
maximum   amount  of  seed   or  fruit  without  attaining 
their  maximum  dimensions.     Plants  grown  for  seed  or 
fruit  are,  therefore,  less  likely  to  be  restricted  in  yield 
by  insufficient  food  than  these  grown  for  their  leaves, 
stems,  roots  or  tubers.     The  cereals,  for  example,  pro- 
duce well  on  land  not  sufficiently  fertile  to  yield  equally 
good  crops  of  tobacco,  cabbage,  celery,  lettuce  or  pota- 
toes.    But  with  a  sufficient  restriction  of  food,  the  seed 
product  will  suffer  diminution  or  be  wholly  cut  off. 

252.  Crop-Growing  Tends  to  Reduce  Plant  Food  in 
the  soil  in  proportion  as  the  fertilizing  components  of 
the  crops  are  removed  from  the  land  and  are  not  re- 
turned  to   it,   directly  or  in   equivalent.     Fortunately, 
considerable  plant  food  is  constantly  being  liberated  by 
the  disintegration  and  decay  of  rock  or  soil  materials, 
or  is  being  deposited  from  the  atmosphere  in  rain  or 
snow,   so   that   it   is   impossible  to   exhaust  the  soil  of 
plant   food,   even   with   the   most   improvident   culture. 
But  the  cultivator  should  aim  at   the   largest  returns 
from  his  soil,  and  these  are  impossible  without  restor- 
ing certain  materials  that  continued  crop-removal  in- 
variably reduces  below  the  limit  of  profitable  yields. 


154  Principles  of  Plant  Culture. 

253.  The  Food  Elements  Most  Likely  to  be  Defi- 
cient, when  plants  are  properly  supplied  with  water, 
are  nitrogen,  phosphorus  and  potassium.     These  are  all 
liberated  in  greater  or  less  quantities,  when  vegetable 
or  animal  material  (organic  matter)  decays  in  the  soil; 
hence  all  such  material  has  more  or  less  value  as  fertil- 
izers.    But   we   need  not   wholly   depend  upon   refuse 
organic    matter    for    fertilizers,    since    the    leguminous 
plants  add  nitrogen  to  the  soil   (259),  and  compounds 
of  nitrogen,  phosphorus  and  potassium  may  often  be 
purchased  in  artificial  fertilizers  at  prices  that  place 
them  within  the  reach  of  the  cultivator. 

254.  Nitrogen   is   the    Most    Important    Fertilizing 
Element  because  it  is  liberated  in  smallest  amount  by 
rock  decay  and  is  most  expensive  in  the  market.     Nitro- 
gen is  chiefly  used  by  plants  in  the  form  of  nitrates, 
i.  e.,  in  combination  with  certain  other  substances  as 
soda,    potash,    lime,    magnesia    and    iron.     Ammonia, 
which  is  a  gaseous  compound  of  nitrogen  and  hydrogen, 
is  also  used  to  some  extent  by  plants.     Free  nitrogen, 
the  most  abundant  constituent  of  the  air,  plays  no  di- 
rect part  in  plant  nutrition  (259). 

255.  The  Sources  of  Nitrates  in  the  Soil  are 

a— Nitrification  (nit-ri-fi-ca-tion),  by  which  the  nitro- 
gen contained  by  organic  matter  and  ammonium  sulfate 
in  the  soil  is  changed  to  nitric  acid  through  the  agency 
of  microscopic  plants  (bacteria).  The  nitric  acid  thus 
formed  combines  with  certain  substances  (bases}  in  the 
soil,  as  potash  and  lime,  forming  nitrates  (254). 

b— Symbiosis  (sym-bi-o-sis)  on  the  roots  of  legumin- 
ous crops,  through  which  atmospheric  nitrogen  is 
changed  to  nitric  acid  (259,  112). 


Plants  as  Affected  by  Insufficient  Food.        155 

c— Deposits   from   the   atmosphere   in   rain   or  snow 

(260). 

d — Ammonium  salts  or  nitrates  applied  to  the  soil 
(261). 

256.  The  Conditions  Affecting  Nitrification  are  sim- 
ilar to  those  affecting  plant  life  in  general,  since  nitri- 
fication results  from  plant  life.     As  it  takes  place  be- 
low the  surface  of  the  soil,  it  is  favored  by  the  same 
conditions  that  favor  the  root  growth  of  land  plants, 
viz.,  aeration,  warmth  and  moisture.     In  general,  it  is 
active  during  the  growing  season,  but  at  a  standstill 
during  the  dormant  period.     It  does  not  proceed  rap- 
idly in    spring  until  the  soil   has    become   sufficiently 
warm  to  promote  active  root  growth. 

Nitrification   also    releases  the   other    food   materials 
contained  by  organic  matter  (92). 

257.  Soil  Aeration  Promotes  Fertility  by  favoring 
nitrification.     Thus  cultivation  and  drainage  (of  heavy 
soils)    not  only  directly  promote  the  growth  of  plants 
by  assisting  aeration    (93),  but  they  actually  increase 
plant  food.     Early  plowing  in  spring  promotes  nitrifi- 
cation  by  favoring  warming  of  the  soil.     Cultivation 
in   dry  weather   further   promotes  plant   nutrition  by 
preventing  the  accumulation  of  soluble  plant  food  in 
the  dry  surface  soil,  where  it   is  deposited  above  the 
reach  of  roots  through  evaporation. 

258.  Partially-Decomposed    Organic    Manures    Act 
More  Promptly  than  fresh  ones,  because  nitrification 
has  already  commenced  in  these  material. 


156  Principles  of  Plant  Culture. 

259.  Leguminous  Plants  Enrich  the  Soil  with  nitric 
acid   (255),  which  is  formed  from  atmospheric  nitro- 
gen in  the  tubercles  on  their  roots  through  the  agency 
of  microscopic   plants    (112).     Even  when   a  part  of 
these  crops  is  removed  from  the  land,  as  when  clover 
is  harvested  for  hay  or  peas  for  their  seed,  the  land  is 
richer  in  nitrogen  than  before  the  crop  was  planted. 
The  principal  leguminous  crops  are  the  clovers,  peas, 
beans,  lentils,  sanfoin,  vetches,  alfalfa,  lupine  and  cer- 
tain species  of  Lathyrus.     Highly  valuable  as  are  these 
crops  for  the  nitrogen  they  leave  in  the  soil,  it  should 
be  remembered  that  they  do  not  contribute  phosphoric 
acid  or  potash,  and  hence  must  not  be  wholly  depended 
upon  for  soil  fertility  (262,  263). 

Leguminous  plants  are  supplied  with  nitrogen  by  the 
micro-organisms  in  their  roots  (112),  and  hence  do  not 
require  this  element  in  fertilizers. 

260.  Rain  and  Snow  Add  Nitrogen  to  the  Soil  in 
small  quantities,  both  as  nitric  acid  and  ammonia,  which 
they  have  taken  from  the  air,  but  the  amounts  thus 
added,  while  useful  to  plants,  are  not  under  our  control. 

261.  Nitrogen  may  be  Purchased  for  fertilizing  pur- 
poses as  sodium  nitrate  (nitrate  of  soda,  Chili-saltpeter), 
ammonium  sulfate  (sulfate  of  ammonia),  and  in  organic 
materials.     The  former  is  available  as  plant  food  when 
dissolved  in  the  soil  water.     It  is  best  applied  imme- 
diately before  the  planting  of  a  crop  or  in  small  quan- 
tities at  intervals  during  growth,  since  it  is  in  danger 
of   being   washed   out   of   the  soil   in  drainage   water. 
Sodium  nitrate  is   especially  useful   for  garden  crops 


Plants  as  Affected  by  Insufficient  Food.        157 

started  early  in  the  spring,  when  the  soil  is  too  cool 
for  active  nitrification  (255).  The  surface  soil  is  apt 
to  be  poor  in  nitrates  in  spring,  because  they  are  often 
washed  down  by  the  autumn  and  winter  rains. 

Ammonium  sulfate  is  changed  to  nitrates  in  the  soil 
before  it  is  used  by  plants,  and  hence  is  less  prompt  in 
its  action  than  sodium  nitrate.  It  is  more  tenaciously 
held  by  the  soil  than  scdium  nitrate  and  is  therefore 
less  likely  to  be  lost  by  washing. 

262.  Phosphorus  is  used  by  plants  in  the  form  of 
soluble   phosphoric    acid,    which    exists   in   the   soil   in 
combination  with  lime,  iron  and  alumina,  as  phosphates 
of  these  substances.     It  may  be  purchased  in  the  form 
of  mineral  phosphate  of  lime,  ground  bone,  wood  ashes, 
odorless   phosphates,   etc.     The  first  two  are  insoluble 
in  water  unless  treated  with  a  strong  acid,  when  they 
are    known    as     acid    phosphate    or    superphosphate. 
Phosphoric  acid  is  not  readily  washed  out  of  the  soil, 
even  in  its  soluble  form. 

263.  Potassium  is  used  by  plants  in  the  form  of  pot- 
ash, i.  e.,  potassium  combined  with  oxygen.     Potash  ex- 
ists  in   the   soil   mainly    in   combination   with   chlorin 
(chlorid  or  muriate  of  potash),  with  sulfurie  acid  (sul- 
fate of  potash),  or  with  nitric  acid  (nitrate  of  potash). 
All  these  forms  of  potash  are  freely  soluble  in  water  and 
are   immediately   available   as   plant   food.     Nitrate  of 
potash   (saltpeter)   is  a  most  valuable  fertilizing  mate- 
rial,  since   it  contains  both  potash   and  nitrogen,  but 
unfortunately  its  price  is  too  high  to  permit  of  its  use 
for  this  purpose.     The  muriate,  either  pure  or  in  crude 
form  (kainit),  and  sulfate  may,  on  the  other  hand,  be 


158  Principles  of  Plant  Culture. 

purchased  at  reasonable  prices.  The  sulfate  is  consid- 
ered preferable  for  tobacco  and  potatoes  as  it  is  thought 
to  produce  a  better  quality  of  product.  The  muriate 
acts  more  promptly  than  the  sulfate,  however. 

264.  Wood  Ashes   are  a  Valuable   Fertilizer,  espe- 
cially when  unleaehed,  as  they  contain  both  potash  and 
phosphoric    acid.     In    leaching,    the    potash    is    mostly 
washed  out,  but  the  phosphoric  acid  is  largely  retained. 
Ashes  contain  no  nitrogen. 

265.  Farm  and  Stable  Manures  should  be  the  first 
dependence  of  the  cultivator.     Aside  from  these,  legu- 
minous crops  (259)  are  undoubtedly  the  cheapest  source 
of  nitrogen   for  the   farm,   and  with   unleached  wood 
ashes,  furnish  all  the  needed  fertilizing  ingredients  for 
grain  crops  grown  in  rotation.     For  garden  crops,  how- 
ever, if  sufficient  stable  manure  can  not  be  obtained, 
more  nitrogen  may  often  be  profitably  used  than  can 
be  furnished  by  leguminous  crops,  hence  for  these,  com- 
mercial fertilizers  may  often  be  added  with  advantage. 

266.  Crops  Suggest  Their  Own   Needs  to  some  ex- 
tent, so  long  as  they  are  not  suffering  from  drought. 
As  a  rule,  a  lack  of  nitrogen  is  indicated  by  pale-green 
foliage  or   small   growth  of  leaf   or  stalk.     Excess   of 
nitrogen  is  indicated  by  very  large  growth  of  leaf  or 
stalk,  with  imperfect  bud-,  flower-  and  fruit  develop- 
ment.    Lack  of  phosphoric  acid  is  indicated  by  scanty 
crops  of  light  or  shrunken  seeds  on  plants  of  normal 
size.     Lack  of  potash  is  indicated  by  small  crops  of  in- 
ferior fruit,  accompanied  by  satisfactory  growth. 

267.  Crop    Rotation    Economizes    Plant    Food,  be- 
cause some  crops  use  more  of  a  given  food  constituent 


Plants  as  Affected  by  Parasites.  153 

than  others.  The  alternating  of  crops  having  different 
food  requirements  tends  to  prevent  the  exhaustion  of 
special  food  substances.  Crop  rotation  also  aids  in 
avoiding  damage  from  injurious  insects  and  fungi. 

268.  A  Growing  Crop  Tends  to  Conserve  Fertility, 
because  it  reduces  drainage  by  taking  up  water  from 
the  soil,  and  at  the  same  time,  appropriates  the  avail- 
able plant  food,  thus  preventing  loss  of  the  latter  from 
leaching. 

269.  Manures  are,  in  part,  the  Raw  Material  from 
which  the  cultivator  turns  out  valuable  products.     They 
should,  therefore,  be  most  carefully  preserved  and  ap- 
plied.    Leaching  of  the  manure  pile  by  undue  expos- 
ure to  rain  and  over-rapid  fermentation,  by  which  ni- 
trogen escapes  as  ammonia  or  other  gaseous  nitrogen 
compounds,  should  be  stringently  avoided.     All  refuse 
organic  matter  should,  so  far  as  possible,  be  made  to 
increase  the  always  too-small  stock  of  manure. 

SECTION  VII.     PLANTS  AS  AFFECTED  BY  PARASITES. 

The  only  instance  of  a  beneficial  plant  parasite  (24) 
of  special  interest  to  the  cultivator,  is  the  micro-organ- 
isms in  the  roots  of  leguminous  plants,  which  we  have 
already  considered  (259).  Many  parasites  of  harmful 
insects  are  beneficial,  but  these  are  beyond  our  scope. 
We  need,  therefore,  to  treat  here  only  those  parasites 
that  are  directly  injurious  to  economic  plants. 

270.  The    Injurious    Parasites    of   plants    are    Very 
Numerous  and  a  scientific  classification  of  them  is  be- 
yond the  limits  of  this  work.     We  shall  only  endeavor 


160  Principles  of  Plant  Culture. 

to  arrange  the  different  parasites  into  groups  based  on 
their  manner  of  working  injury  and  the  methods  by 
which  they  may  be  controlled. 

With  reference  to  the  character  of  their  injury  and 
the  preventives  used,  as  well  as  in  their  natural  char- 
acteristics, plant  parasites  are  readily  separable  into 
two  great  classes,  viz.,  animal  and  vegetable  parasites. 
These  classes  will  be  considered  in  their  order. 

A  —  PLANTS  AS  AFFECTED  BY  ANIMAL  PARASITES. 

a  —  By  quadrupeds  and  birds.  The  four-footed 
animals  that  injure  cultivated  crops  nearly  all  belong  to 
the  class  known  as  rodents,  which  includes  mice,  go- 
phers, rabbits,  woodchucks,  moles,  etc.  These  may 
usually  be  controlled  by  trapping,  shooting,  or  poison- 
ing, or  by  protecting  the  plants. 

271.  Damage  from  Mice  to  orchard  and  nursery 
trees  is  very  common.  Mice  are  usually  more  trouble- 
some on  sod  ground  covered  with  snow,  especially  be- 
neath snow  banks,  hence  all  grass  should  be  removed  in 
autumn  from  the  immediate  vicinty  of  the  trees.  It 
is  well  to  ridge  the  soil  a  little,  directly  about  the  trees, 
so  that  the  mice  in  burrowing  beneath  the  snow  will 
not  be  likely  to  come  in  contact  with  the  stems.  Pack- 
ing the  snow  immediately  about  the  trees  is  helpful 
when  damage  is  discovered  during  winter.  The  stems 
of  orchard  trees  may  also  be  wrapped  in  heavy  paper 
or  inclosed  in  fine  wire  netting.  If  tarred  paper  is  used, 
it  should  be  promptly  removed  in  spring,  or  it  may  in- 
jure the  bark. 


Plants  as  Affected  by  Animal  Parasites.        161 

Stored  seeds  of  almost  all  kinds  must  be  carefully 
guarded  against  mice. 

272.  Gophers     are     often     troublesome     by     eating 
planted  seeds   and  by   burrowing   about   the   roots  of 
ycung  orchard  trees.    .They  may  be  poisoned  by  plac- 
ing corn,  soaked  in  a  weak  solution  of  strychnine  in 
water,  about  their  holes. 

273.  Rabbits  are  especially  troublesome    to    nursery 
trees,    when    the    ground   is   covered  with   snow.     The 
most   satisfactory  protection  is  to  inclose  the  nursery 
with  a  fence  of  poultry  netting,  which  should  be  banked 
up  a  little  at  the  bottom  to  prevent  the  rabbits  from 
passing  under.    It  should  be  high  enough  to  reach  above 
the  surface  of  the  deepest  snow. 

Orchard  trees  may  be  protected  against  rabbits  by 
inclosing  the  trunks  with  the  devices  mentioned  under 
sun-scald  (185.) .  Smearing  the  stems  with  blood  has 
also  been  recommended. 

274.  Woodchucks  are  often  troublesome  to  growing 
crops,  but  as  they  are  seldom  numerous,   shooting  or 
trapping  generally  suffices  to  prevent  serious  damage. 
Moles  are  very  troublesome  in  some  localities  by  eating 
the  roots  of  plants.     They  may  be  largely  controlled  by 
the  use  of  mole-traps.     Pouring  a  little  carbon  bisulfid 
into  their  holes  is  also  generally  effectual. 

275.  Birds   are   often  troublesome  by  eating  unhar- 
vested  fruits  and  seeds.     Inclosing  the  trees  or  plants 
with  fish  netting,  when  this  is  practicable,  is  perhaps 
the   most  satisfactory  preventive.     The  netting  is  not 
expensive,    and   the   same  piece  may   be  used   several 
seasons. 


162  Principles  of  Plant  Culture. 

b  —  By  insects,  worms,  slugs  and  snails.     As 

worms,  slugs  and  snails  work  the  same  kind  of  injuries 
as  some  insects  and  are  controllable  by  the  same  meth- 
ods, we  do  not  distinguish  between  them  in  the  follow- 
ing paragraphs. 

276.  Many    Insects    are    Beneficial    by    destroying 
harmful  insects  or  by  promoting  pollination   (150).  We 
should  not,  therefore,  wage  indiscriminate  warfare  upon 
all  insects. 

277.  Methods    of    Preventing    Insect    Ravages    to 
plants  are   various,   as  inclosing  the  plants,   trapping, 
repelling  or  -removing  the  insects,  destroying  them  by 
means   of   insecticides,   or  preventing   reproduction  by 
destroying  vthe   eggs.     The   important   question   in   the 
case  of  any  injurious  insect  is  by  which  one  of  these 
methods  it  may  be  most  effectually  and  cheaply  con- 
trolled. 

278.  Inclosing   the    Plants   is  practicable  in   a   few 
cases,  as  with  the  striped  cucumber  beetle.*     The  hills 

in  which  cucumbers, 
melons,  squashes,  etc., 
are  planted,  may  be 

FIG.  67.      Screen-covered    frame    for  pnvprp^     with       ,      frflrrlp 
protecting    hills    of     the    melon    and  COV6r' 

having  fine-meshed  wire- 

or  cotton  netting  tacked  over  the  top,  which  prevents 
the  beetles  from  gaining  access  to  the  plants  (Fig.  67). 

279.  Trapping  the   Insects   is   practicable  in  a  few 
cases,  as  with  cutworms,  which  often  conceal  themselves 
during  the  day  beneath  objects  on  the  ground.     They 
will  frequently  be  found  in  numbers  beneath  handfuls 

*Diabrolica  vittaia. 


Plants  as  Affected  by  Animal  Parasites.         163 

of  green  clover  or  other  herbage  placed  on  the  ground 
near  the  plants  which  it  is  desired  to  protect.  By  pois- 
oning the  herbage  (283),  some  of  the  cutworms  may  bo 
killed,  but  many  are  likely  to  escape  unless  destroyed 
by  other  means. 

280.  Repelling  Insects  by  means  of  offensive  odors  is 
partially   effective  in  some  cases,   as  with  the  squash- 
vine  borer.*     Corncobs  or  other  objects,  dipped  in  coal 
far  and  placed  among  the  plants,  repel  many  of  the 
moths  that  produce  the  borers. 

281.  Hand  Picking,  i.  e.,  removing  the  insects  from 
the  plants  by  hand,  is  the  most  satisfactory  method  for 
destroying   certain   insects,    as   the  tobacco-   or  tomato 
wormj  and  other  large  caterpillars,  and  the- rose-beetle. $ 
A  vessel  of  water  with  a  little  kerosene  on  the  surface, 
in  which  to  throw  the  insects  as  they  are  gathered,  is  a 
convenient  way  of  destroying  them.     In  some  cases,  the 
insects  can  be  shaken  or  knocked  from  the  plant  directly 
into  the  vessel.     This  method  is  often  employed  in  de- 
stroying the  potato  beetle.  §     Digging  out  cutworms  and 
white  grubs**  from  about  corn  and  strawberry  plants, 
and  cutting  out  borers  from  trees  and  squash  vines  are 
often  the  most  effectual  methods  for  destroying  these 
insects. 

282.  Destroying   Insects  by  Poisons  or  Caustics  is 
the    method  most    generally    available.     The    material 
used  is  called  an  insecticide  (in-sect'-i-cide),  and  if  sat- 
isfactory, must  be  destructive  to  the  insects  without  in- 
juring the  plant  to  which  it  is  applied,  or  rendering 

*  Melitia  ceto.        \  Phlegethonlius  celeus.        %  Macrodactylus  subspinosus. 
I  Doryphora  decemlineata.       **  Lachnosterna. 


164  Principles  of  Plant  Culture. 

the  plant  or  its  products  unfit  for  food.  The  insecti- 
cides in  most  general  use  are  certain  compounds  of 
arsenic  (Paris  green,  London  purple,  white  arsenic), 
hellebore  and  pyrethrum  powders,  tobacco,  kerosene 
and  various  compounds  of  soda  and  potash.  With  the 
exception  of  kerosene  and  the  soda  and  potash  com- 
pounds, all  these  may  be  used  either  as  dry  powder  or 
with  water. 

283.  The  Arsenic  Compounds  are  effectual  as  insect 
destroyers,  even  when  largely  diluted.     When  applied 
in  water,  however,  they  are  liable  to  injure  foliage  in 
proportion  to  the  amount  of  soluble  arsenic  they  con- 
tain.    When  insoluble  in  water,  they  require  stirring 
to  keep  them  in  suspension. 

284.  Paris  Green  (arsenite  of  copper),  when  pure,  is 
a  nearly  insoluble  compound  and  may  be  safely  used 
upon  the  foliage  of  most  plants,  diluted  at  the  rate  of 
one  pound  to  two  hundred  gallons  of  water.     For  the 
peach  and  nectarine  it  should  be  diluted  one-half  more. 
Pure  Paris  green  dissolves  without  sediment  in  ammo- 
nia water. 

285.  Arsenite   of  Lime,   a  very  cheap  arsenic  com- 
pound, may  be  prepared  by  boiling  one  pound  of  pow- 
dered white  arsenic  and  two  pounds  of  fresh  lime  in 
two  gallons  of  water  for  twenty  minutes,  stirring  occa- 
sionally.    For    use  -dilute   to   400   gallons.     This   costs 
only  one-fourth  as  much  as  Paris  green. 

286.  Arsenate  of  Lead  contains  less  soluble  arsenic 
than  Paris  green  and  remains  longer  in  suspension.     To 
prepare  arsenate  of  lead*  "dissolve  24  ounces  of  ace- 

*  Bulletin   151,   California   Agricultural   Experiment  Station. 


Plants  as  Affected  by  Animal  Parasites.        165 

tate  of  lead  (sugar  of  lead)  in  one  gallon  of  water  and 
separately  10  ounces  of  arsenate  of  soda  in  three  quarts 
of  hot  water.  (Use  wooden,  earthen  ware  or  glass  ves- 
sels.) Pour  the  separate  solutions  into  100  gallons  of 
water.  A  white  precipitate  of  lead  arsenate  ready  for 
spraying  immediately  forms  in  the  tank;  its  fine,  floc- 
culent  condition  keeps  it  in  suspension  for  hours,  and 
of  all  arsenic  compounds  it  is  the  most  easily  kept  sus- 
pended in  water." 

Arsenate  of  lead  prepared  ready  for  use  is  offered 
under  different  trade  names,  as  "Disparene,"  etc. 

287.  London  Purple    (arsenite  of  lime,  with  certain 
impurities)    often    contains    soluble    arsenic    and    like 
white  arsenic,  must  be  used  with  caution.     It  may  be 
safely  applied  to  many  p7ants  at  the  rate  of  one  pound 
to  two  hundred  gallons  of  water,  if  put  on  immediately 
after  its  addition  to  the  liquid,  but  for  the  peach  it 
should  receive  greater  dilution.     London  purple  is  con- 
siderably cheaper  than  Paris  green. 

The  addition  of  fresh  milk  of  lime  to  water,  to  which 
white  arsenic  or  London  purple  has  been  added,  largely 
prevents  their  tendency  to  injure  foliage. 

Both  Paris  green  and  London  purple,  when  perfectly 
mixed  with  150  parts,  by  weight,  of  land  plaster,  or  an 
equal  bulk  of  any  other  cheap,  harmless  powder,  are 
satisfactory  for  destroying  the  potato  beetle  and  many 
other  leaf -eating  insects  (307). 

288.  Compounds  of  Arsenic  are  Deadly  Poisons  and 
should  always  be  handled  with  the  greatest  care. 


166  Principles  of  Plant  Culture. 

289.  Hellebore     (hel'-le-bore)     Powder,     i.     e.,    the 
ground  root  of  white  hellebore,*  is  a  far  less  virulent 
poison   than    the   arsenic   compounds.     It   is   therefore 
useful  in  destroying  a  class  of  insects  against  which  a 
deadly  poison  cannot  wisely  be  used,  as  the  imported 
currant  worm,f  and  the  cabbage  caterpillar.  $ 

Hellebore  powder  when  used  dry,  may  be  diluted 
with  once  or  twice  its  bulk  of  flour,  which  causes  it  to 
adhere  better  to  the  foliage  than  if  used  alone.  When 
applied  with  water,  a  heaping  teaspoonful  or  more  may 
be  added  to  three  gallons.  The  dry  powder  is  very 
light  and  should  only  be  used  in  a  still  atmosphere. 

A  decoction  made  by  boiling  the  root  of  white  helle- 
bore in  water  is  said  to  possess  insecticide  properties 
similar  to  those  of  the  powder. 

290.  Pyrethrum    (py-re'-thrum)     Powder,    (Persian 
insect   powder,  Dalmatian   insect   powder,   Buhach)    is 
the  pulverized  flowers  of  certain  species  of  Pyrethrum.  § 

Pyrethrum  powder  is  not  poisonous  to  the  higher  ani- 
mals, but  the  oil  that  pervades  it  is  destructive  to  many 
insects.  As  the  oil  is  extremely  vo^tile,  pyrethrum  is 
better  adapted  for  use  under  glass  or  with  plants  other- 
wise inclosed.  It  is  not  injurious  to  foliage  or  flowers. 
Fresh  and  pure  pyrethrum  powder  may  be  diluted  half 
or  more  in  bulk  with  any  other  light,  cheap,  harmless 
powder,  but  the  mixture  should  stand  a  day  or  two  be- 
fore use,  to  enable  the  diluent  to  absorb  the  oil.  The 

*  Veralrum  album.       f  Nematus  rtbeM.       %  Pieris  rapce 

?  "Persian  insect  powder"  is  made  from  the  flowers  of  Pyre- 
thrum roseum  and  P.  carneum;  "Dalmatian  insect  powder"  and 
"Buhach"  are  made  from  those  of  P.  cineraioefolium.  "Buhach" 
is  the  trade  name  of  a  pure  product  prepared  in  California. 


Plants  as  Affected  by  Animal  Parasites.        167 

powder  may  be  used  with  water  at  the  rate  of  half  a 
pound  to  three  gallons. 

The  pyrethrum  plant  is  comparatively  hardy  and  has 
been  successfully  grown  in  northern  United  States.  It 
is  said  that  a  decoction  of  the  unopened  flowers  posses- 
ses the  insecticide  properties  of  the  commercial  product. 

291.  Hellebore  and   Pyrethrum   Powders  should  be 
Kept  in  Close  Vessels,  since  their  poisonous  properties 
are  volatile.     In  purchasing,  only  fresh  samples  should 
be  accepted.     If  fresh  and  pure,  these  powders  produce 
a  tingling  sensation  when  applied  to  the  nostrils. 

292.  Tobacco   Smoke   is  much   used   for   destroying 
"lice"  or  "green  fly"  (aphida?)  on  plants  under  glass. 
For  this  purpose,  the  partially-dry  stems  or  leaves  are 
burned   upon   pans    or   bricks,    or   in   small   sheet-iron 
stoves.     Many  delicate  flowers  are,  however,  injured  by 
tobacco  smoke.' 

Stems  or  leaves  of  tobacco,  strewn  abundantly  be- 
neath greenhouse  benches,  tend  to  prevent  the  mulit- 
plication  of  aphidee. 

Several  semifluid  extracts  of  tobacco  are  sold  which 
may  be  evaporated  in  the  greenhouse  over  an  oil  stove, 
or  preferably  by  steam  under  pressure.  Some  of  these 
are  very  efficient  for  destroying  insects  and  do  not  in- 
jure flowers. 

293.  A  Strong  Decoction  of  Tobacco  is  often  used 
for  destroying  aphidse  on  plants  in  rooms  where  tobacco 
smoke    would    be    objectionable.     The    plants    are    im- 
mersed in,  or  washed  with  the  decoction.     The  same  is 
often  effectually  used  on  young  plants  of  cabbage,  cau- 


168  Principles  of  Plant  Culture. 

liflower  and  turnip,  to  prevent  their  destruction  by  the 
flea  beetle.* 

294.  Kerosene  is  a  very  useful  insecticide  for  a  class 
of  insects  not  readily  destroyed  by  other  means  (316). 
It  has  generally  been  used  as  an  emulsion  made  with 
soap  and  water,  for  which  the  following  formulas  are 
good. 

a — Dissolve  one  quart  of  soft  soap,  or  one-fourth 
pound  of  good  hard  soap,  in  two  quarts  of  boiling 
water;  remove  from  the  fire,  and  pour  into  a  can  con- 
taining one  pint  of  kerosene.  Agitate  violently  in  the 
can  for  three  minutes.  For  use,  dilute  with  an  equal 
quantity  of  water;  or 

b — Dissolve  one-half  pound  of  hard  soap  in  one  gal- 
lon of  boiling  soft  water;  add  at  once  two  gallons  of 
kerosene,  and  churn  or  otherwise  violently  agitate  for 
five  or  ten  minutes.  For  use,  dilute  with  15  parts  of 
soft  water. 

Kerosene  may  also  be  applied  in  intimate  mixture 
with  water,  secured  by  pumping  both  liquids  at  once 
through  a  good  spraying  nozzle  (Fig.  70).  About  ten 
per  cent,  of  kercsene  should  be  used  for  most  plants. 

295.  Caustic  Potash  in  solution  is  useful  for  destroy- 
ing certain  scale  insects,  as  the  oyster-shell  bark-louse,v 
for  which  solutions  of  one-fourth  pound  to  the  gallon 
of  water  may  be  applied  during  winter. 

296.  Resin  (or  rosin)  Washes  are  valued  for  destroy- 
ing various  scale  insects  in  southern  and  western  United 
States.     They  are  adapted  with  modifications  to  both 
dormant   and   growing  trees.     The   resin  is   sometimes 

*Phyllotreia  vittala.       ^  Mytilaspis  pomorum. 


Plants  as  Affected  by  Animal  Parasites.        169 

saponified  with  caustic  soda  and  simply  diluted  with 
water;  fish  oil  or  petroleum  may  also  be  added.  The 
following  and  other  formulas  are  in  use: 

a— Dissolve  one  pound  of  caustic  soda  in  one  gallon 
of  water  in  a  covered  iron  kettle.  Pour  out  half  of  the 
solution,  and  to  the  remainder  add  8  pounds  of  resin 
and  boil  until  dissolved.  Then  pour  in  very  slowly  the 
rest  of  the  caustic  soda  solution  and  boil  the  whole, 
stirring  it  constantly,  until  it  will  unite  with  water, 
forming  a  liquid  resembling  milk.  Dilute  to  22  gallons 
for  use.  This  mixture  may  be  applied  during  the  grow- 
ing season ;  or 

b— Place  30  pounds  of  resin,  9  pounds  of  70  per  cent 
caustic  soda  and  4y2  pints  of  fish  oil,  in  a  closed  iron 
kettel  and  cover  with  five  or  six  inches  of  water.  Boil 
until  the  liquid  has  a  dark-brown  color,  after  which 
slowly  add  water  until  the  whole  makes  100  gallons ;  or 
dilute  a  part  of  the  liquid  at  this  rate,  keeping  the  re- 
mainder as  a  stock  solution.  This  is  for  use  in  the  dor- 
mant season.  For  the  growing  season,  similar,  but  more 
dilute  solutions  are  used. 

297.  Hydrocyanic  Gas.  Another  method  of  destroy- 
ing scale  insects  is  to  treat  the  tree,  previously  inclosed 
in  an  oil-cloth  tent,  with  hydrocyanic  gas.  One  ounce 
of  cyanid  of  potassium  and  one  measured  ounce  of  sul- 
furic  acid  are  placed  in  an  earthen  or  leaden  jar  con- 
taining three  fluid  ounces  of  water.  The  jar  is  covered 
with  burlaps  to  prevent  the  rapid  escape  of  the  gas. 
The  tent  is  left  over  the  tree  fifteen  minutes  to  one 
hour.  It  is  advisable  to  apply  this  treatment  during 
the  dormant  season  and  in  a  cool  period.  Nursery 


170  Principles  of  Plant  Culture. 

stock  is  now  required  by  law  in  some  localities  to  be 
treated  with  hydrocyanic  gas  before  shipment,  to  pre- 
vent the  dissemination  of  dangerous  scale  insects. 

298.  Fir-Tree  Oil  is  considerably  used  in  greenhouses 
and  conservatories  for  destroying  scale  insects  and  the 
mealy  bug.*    .It  is  mixed  with  warm  soft  water  at  the 
rate  of  a  tablespoonful  of  oil  to  a  pint,  and  applied 
with    a    syringe;    or   the   plants    are   dipped    into    the 
mixture. 

299.  Hot  Water  may  also  be  used  for  destroying  the 
above  named  insects    (298)    and   plant  lice    (aphidas). 
Infested  pot-plants  are  inverted  and  immersed  five  or 
six  seconds   in  a  vessel  containing  water  at   120°    F. 
This  treatment  must  be  used  with  caution. 

Forcible  syringing  of  plants  with  water  is  also  an 
excellent  method  of  ridding  greenhouse  plants  from 
insects. 

300.  Insect    Attacks    Sometimes    Become    Formid- 
able from  the  vast  number   of  the  individuals.     The 
chinch-bug,t   the   army-worm$    and  various  species   of 
locusts    or    grass-hoppers    sometimes     devastate    large 
tracts  of  country.     For  the  destruction  of  these  insects, 
special  means  must  be  employed. 

301.  The  Chinch-Bug  may  be  controlled  in  a  meas- 
ure, by  burning  over  all  grass  land  early  in  spring,  in 
seasons  when  attacks  are  expected.     The  bugs  may  be 
kept  out  of  corn  fields  by  plowing  a  furrow  away  from 
the  corn,  on  the  side  from  which  the  attack  is  looked 
for,  and  strewing  stalks  of  fresh  corn  in  this.     As  the 
insects  congregate  on  the    corn   in    the    furrow,  they 

*  Dactylopius.       f  Bllssus  leucoplerus.       I  Leucania  unipuncta. 


Plants  as  Affected  by  Animal  Parasites.        171 

should  be   destroyed   with  kerosene    (294).     Persistent 
and  thorough  work  is  essential  to  success. 

302.  The  Army-Worm  may  often  be  prevented  from 
migration  by  plowing  a  deep  furrow,  as  above  directed, 
and  making  the  side  toward  the  endangered  crop  verti- 
cal, with  a  spade  or  shovel.     The  insects  will  congregate 
in  the  furrow  where  they  may  be  destroyed  by  drag- 
ging a  log  over  them. 

303.  Grasshoppers   and   Locusts  may  be   destroyed, 
before  they  have  attained  their  wings,  by  drawing  over 
the  infested  ground  a  "hopper-doser,"  which  consists 
of  a  shallow,  sheet-iron  pan,  with  a  vertical,  cloth-cov- 
ered back.     The  pan  contains  a  little  kerosene,  and  the 
cloth  back  is  kept  saturated  with  the  same  liquid.     The 
insects  jump  into  the  pan  or  against  the  cloth  back, 

thus  becoming  wet  with  the  kerosene, 
and   soon    perish.     Grasshoppers   may 
also  be  poisoned  by  dis- 
tributing bran  mixed  into 
!B  a  mash  with  water  con- 
taining   arsenic    in    solu- 
tion. Plowing  grass  land 
I      containing   the     eggs    of 
grasshoppers      tends      to 
A  prevent  an  attack. 

304.     Apparatus      for 
Applying       Insecticides. 

BIO.  68.  sifting  box  for  apppiy-  Po^ers  are  readily  ap- 
ing powders.  plied  to  low-growing 
plants,  as  the  potato,  cabbage,  etc.,  by  means  of  a  sift- 
ing box  consisting  of  a  pail  with  a  perforated  bottom, 


172  Principles  of  Plant  Culture. 

a  rigid  handle  and  a  tight-fitting  cover  (Fig.  68).  For 
small  plants,  as  young  potato  tops,  the  tin  disc  A  which 
has  a  circular  hole  in  the  center,  is  laid  inside  on  the 
bottom  of  the  box,  and  held  in  place  by  small  lugs 
soldered  to  the  wall  as  shown.  When  it  is  desired  to 
spread  the  powder  more,  the  disc  B  is  used. 

For  taller  plants,  a  powder  bellows  is  desirable. 

Liquids  are  best  distributed  with  a  force  pump,  fit- 
ted with  a  hose  of  a  length  suitable  to  the  height  of  the 
tree  or  plant,  and  with  an  atomiz- 
ing nozzle  (Figs.  69,  70,  71).  For 


FIG.   69.  FIG. 


FIG.  69.  A  convenient  and  serviceable  spray  pump,  using  a 
common  pail  for  a  reservoir. 

FIG.  70.  A  similar  pump  with  attachment  by  which  kerosene 
and  water  may  be  sprayed  together  (294).  Both  are  made  by 
the  Deming  Co.,  Salem,  Ohio. 

tall  trees,  the  hose  nozzle  may  be  elevated  by  attaching 
it  to  the  end  of  a  light  pole.  In  orchard  spraying,  the 
pump  is  often  used  on  a  wagon,  and  the  man  holding 
the  hose  sometimes  stands  on  a  high  platform.  A  spray 
pump  used  on  a  large  reservoir,  needs  an  agitator  to 


Plants  as  Affected  by  Animal  Parasites.         173 


prevent  the  heavier  part  of  the  spraying  mixture  from 
settling. 

Excellent  bellows  and  force  pumps,  designed  ex- 
pressly for  applying  insecticides,  are  now 
manufactured. 

305.  The  Use  of  Insecticides.  In  treat- 
ing any  given  insect,  the  most  important 
question  to  decide,  is  the  manner  in  which 
it  appropriates  its  food,  as  upon  this  will 
depend  the  preventive  measures  to  be 
used. 

306.  Injurious  Insects  are  refer- 
able to  Two  Classes,  viz., 
eating  insects,  i.  e.,  those 
feeding  directly  upon  the 
plant  tissues,  as  the  potato 
beetle,  the  apple-tree  borers,* 
the  plum  curculio;f  and  the 
i  sucking  insects,  i. 

e.,  those  feeding 
only  upon  the 
juices  of  the  plant, 
as  plant  lice,  the 
squash-bug,J  and 
the  oyster-shell 
bark-louse.  § 

307.  The  Eating 
Insects     may     be 
subdivided  into  leaf-eaters,  those  that  devour  the  foli- 

*  The  round-headed  apple-tree  borer.   Saperda  Candida;   the  flat- 
headed    apple-tree   borer,  Chrystibothrix  ffinorata. 

\Conotrachelusnenuphar.         f  Anaxa  trutis.         $  Mylilaspis  pomorum 


FIG.  71.  Steam 
factored  by  (the 
Rochester,  N.  Y. 


spraying    outfit,    manu- 
Shipman     Engine     Co.. 


174 


Principles  of  Plant  Culture. 


age;  root-eaters,  those  that  devour  the  roots;  and  bur- 
rowers,  those  that  harbor  within  some  part  of  the  plant 
by  eating  a  passage  for  their  bodies. 

308.  The     Leaf-Eaters     include    numerous     species. 
They  are  readily  recognized  by  the  fact  that  the  leaves, 
on  which  they  feed,   disappear  more  or  less  rapidly. 
They  may  generally  be  destroyed  by  applying  a  poison 
to  the  foliage,   for  which   purpose  the   arsenical  com- 
pounds are  well  adapted    (283).     In  cases  where  the 
use  of  a  deadly  poison  is  unsafe,  hellebore    (289)    or 
pyrethrum  (290)  may  be  substituted. 

309.  The  Root-Eaters  include  fewer  species  than  the 
leaf-eaters  and  are  usually  more  difficult  to  control. 

-.  ;^  Carbon  bisulfid,   injected  into   the  soil 

about  the  roots  of  cabbage  and  cauliflower 
plants,   with    an   instrument    devised    for 
the  purpose    (Fig.  72),  has  been  success- 
fully used  to  destroy  the  cabbage  maggot,* 
and  may  be  found  useful  in  other  cases. 
Attacks  of  this  insect  have  also  been  suc- 
cessfully  prevented  by   surround- 
|".  ing  the  stem  of  the  young  plant 
with   small    cards   of   thin   tarred 
paper.     One   of   these    cards,   the 
[n   tool   used   for   cutting   them,   and 
l£j  the  manner  of  using  the  tool  are 
shown  in  Figs.  73,  74  and  75. 

310.  Burrowers,  as  the  term  is  here  used,  include 
not  only  the  so-called  borers  that  burrow  within  the 
stems  and  roots  of  plants,  and  the  leaf  miners,  that 

*  Phorbia  brassicce. 


FIG.    72.     Tool  for 


plants- 


Plants  as  Affected  by  Animal  Parasites.        175 

live  between  the  surface  of  leaves,  but  also  the  insects 
that  pass  their  larval  stage  within  fruits.  Insects  of 
this  class  are  difficult  to  control,  since  they  are  mostly 
beyond  the  reach  of  insecticides. 

311.  Borers  that  infest  the  trunks  and  main  branches 
of  trees,  may  often  be  kept  out  by  applying  strong  al- 
kaline washes  to  these  parts.  Soft  soap  reduced  to  the 
consistency  of  thick  paste  by  a  strong  solu- 
tion of  washing  soda,  applied  to  the  trunk 
or  branches,  forms  a  rather  tenacious  coat- 
ing which  repels  the  female  insect.  Paint- 
ing the  trunks  of  small  apple  trees  a  short 
distance  above  and  below  the  surface  of  the 
ground  with  common  paint  or  pine  tar,  is 
said  to  prevent  the  entrance  of  the  round- 
headed  borer  (306).  Protect- 
ing the  trunk  with  straw  or 
lath,  as  recommended  to  pre- 
vent sun-scald 
(185)  may  tend 
to  keep  out 
these  insects. 
Borers  in  the 
trunk  can  often 
be 


flower    plants.     Reduced    one-half. 


pl 

FIG.  74.     Tool  for  cutting   the   cards. 
FlG-  75-     Manner     of    using     the     tool.     The 
dotted  lines  show  the  position  of  the  edge  of 

probing   their    l      t001  on  the  paper' 
holes  with  a  flexible  twig. 

312.  Leaf-Miners  often  infest  spinach  and  beets 
grown  for  greens,  rendering  the  leaves  unfit  for  use. 
For  these  insects  we  can  offer  no  preventive  measures 


176  Principles  of  Plant  Culture. 

of  established  value.  The  application  to  the  young 
foliage  of  powerful  odorants,  as  coal-tar  water  or  a 
solution  of  carbolic  acid,  may  prove  beneficial. 

313.  The     Codling-Moth,*     which     causes    so-called 
"wormy"  apples  and  pears,  is  controlled  by  spraying 
the  trees  at  the  time  of  egg  deposit,  with  water  contain- 
ing Paris  green   (284).     The  first  spraying  should  be 
given  as  soon  as  the  petals    (142)    fall,  to  be  followed 
by  a  second  six  to  ten  days  later.     If  much  rain  falls 
at  this  season,  the  sprayings  may  need  frequent  repeti- 
tion.    A  drop  of  poisoned  water  should  be  lodged   in 
the  calyx  (141)  of  every  fruit,  and  as  this  evaporates, 
the  poison  deposited  on  the  skin  kills  the  newly-hatched 
insect  as  it  eats  its  way  inward. 

A  band  of  cloth  or  paper,  placed  about  the  trunk  of 
fruiting  apple  or  pear  trees  forms  a  convenient  retreat 
for  larvas  of  the  codling-moth,  in  which  to  pupate. 
They  may  then  be  readily  destroyed  by  removing  the 
band.  The  bands  should  be  a  few  inches  wide,  and 
should  be  put  on  before  midsummer.  They  should  be 
taken  off  once  in  ten  to  fourteen  days,  until  the  fruit 
is  harvested,  and  all  cocoons  beneath  them  should  be 
crushed. 

314.  The  Plum  Curculio   (306)   that  so  often  stings 
young  plums,  causing  them  to  drop  before  maturity,  is 
controlled  by  jarring  the  beetles,  that  deposit  their  eggs 
in   the   young   fruit,   upon   sheet-covered    frames   very 
early  on   cool,  still  mornings  while  their  muscles  are 
stiff    (Fig.   76).     The  jarring  should  begin   almost  as 
soon  as  the  petals    (142)   fall  and  should  be  repeated 
every  still  morning  as  long  as  any  beetles  are  found. 

*  Carpocapsa  pomonella. 


Plants  as  Affected  by  Animal  Parasites.        177 

Any  light  wood  frame,  covered  with  cloth  may  be  used 
as  a  substitute  for  the  more  convenient  device  shown 
in  the  figure.  Where  the  substitute  is  used,  the  beetles 

must  be  looked  for  on 
the  sheet  and  de- 
stroyed as  found. 

315.  The  Prompt 
Destruction  of  Iti- 
fested  Fruit  mate- 

FiG.    76.    Curculio    catcher.    It  is  wheeled      .    ,,          .,      .       , 
beneath    the    branches    of    the    tree,    and    rialJy    aids    in    KCep- 
the  latter  are  struck  with  a  light,  cloth-    .  „      .    , 

covered  mallet,  which  jars  the  beetles  ing  the  iruit-bur- 
upon  the  sheet-covered  frame,  from 

which    they    roll    into    the    box    beneath,    rowing       insects       in 
For     small     trees,     the     trunk     slips     in 
through    the   slot   at  the   left.  subjection.         H  O  g  S 

and  sheep  in  the  orchard  are  most  valuable  assistants  in 
this  work.  The  apple-maggot*  is  more  effectually  con- 
trolled in  this  manner  than  by  any  other  known  method. 

316.  Sucking  Insects  include  many  species.  They 
feed  on  the  juices  of  the  plant  which  they  infest,  and 
do  not  directly  devour  its  tissues,  as  do  the  eating  in- 
sects; but  they  reduce  its  vitality  by  their  continual 
drain  upon  the  reserve  food.  The  so-called  scale  in- 
sects belong  to  this  class.  These  are  especially  difficult 
to  destroy,  since  they  are  dormant  the  greater  part  of 
the  year,  and  in  this  condition  are  protected  by  their 
comparatively  resistant  scales. 

Sucking  insects  are  not  susceptible  to  poisonous  in- 
secticides, hence  we  must  resort  to  materials  that  clog 
their  breathing  pores,  as  kerosene  (294),  that  dissolve 
their  eggs  and  scales,  as  potash  solutions  or  that  form 

*  Trypela  pomonella. 


178  Principles  of  Plant  Culture. 

an   air-tight   coating  over  them,   as   the  resin   washes 
(295).* 

317.  The  Life  Histories  of  Injurious  Insects,  which 
can  not  here  be  taken  up,  may  profitably  be  studied  by 
the  plant  grower.     A  standard  work  on  economic  ento- 
mology will  furnish  the  needed  information. 

B  —  PLANTS  AS  AFFECTED  BY  VEGETABLE  PARASITES. 

318.  Many  of  the  most  serious  enemies  of  cultivated 
plants  belong  to  this  class.     As  a  rule,  vegetable  para- 
sites contain  no  chlorophyll,  and  hence  are  incapable  of 
forming  their  own  food.     While  most  of  them  belong 
to  the  lower  orders  of  plants,  a  few  species  are  highly 
developed  and  produce  true  flowers  and  seeds. 

a  —  By  Flowering  or  phanerogamic  (phan'-er-o- 
ga'-mic)  parasites. 

Of  these,  the  only  ones  sufficiently  common  or  inju- 
rious to  need  mention  are  the  broom  rape  and  the 
dodders. 

319.  The   Broom  Rape  of  Hemp  and   Tobacco,f  is 
the  most  injurious  species  of  this  class.      The  seeds  ger- 
minate in  the  soil,  and  the  young  plants  attach  them- 
selves to  the  roots  of  their  host  which  they  enfeeble  by 
robbing  them   of  nourishment.     In  the   case  of  hemp, 
the  parasite  also  injures  the  quality  of  the  fibre. 

Preventives.  The  seed  of  hemp  or  tobacco  should  not 
be  taken  from  a  crop  infested  with  broom  rape.  In- 
fested fields  should  be  planted  for  several  years  to 

*  The  cottony  cushion  scale,  Icerya  purchasi.  which  was  very 
destructive  to  the  orange  in  California,  has  been  nearly  suppressed 
by  the  introduction  of  an  Australian  parasite,  the  Vedalia  cardin- 

t  Philipcea  ramona. 


Plants  as  Affected  by  Fungous  Parasites.        179 

some  crop  not  attacked  by  broom  rape,  as  potatoes,  Iii- 
dian  corn,  beans,  grains  or  grasses.  In  infested  crops, 
the  broom  rape  should  not  be  permitted  to  mature  its 
seeds. 

320.  The  Dodders  of  Clover  and  Flax,*  are  the  most 
injurious  of  their  class.     The  young  plant  attaches  it- 
self to  the  stem  of  its  host,  about  which  it  twines,  rob- 
bing it  of  nourishment  by  means  of  small  suckers. 

Preventives.  The  seeds  of  dodder  are  somewhat 
smaller  than  those  of  clover  or  flax,  and  hence  may 
be  separated  from  the  latter  by  sifting.  Badly  infested 
ground  should  be  devoted  for  two  to  four  years  to  a 
crop  not  attacked  by  the  dodder. 

b  —  Plants  as  affected  by  fungous  parasites. 

321.  The    Fungi    constitute    an    extensive    class    of 
plants  that  derive  their  nourishment  wholly  from  or- 
ganic matter.     Many  of  them  are  injurious  to   culti- 
vated plants.  Unlike  the  harmful  insects,  most  of  which 
work  their  ravages  within  full  view,  the  fungi  are  in 
many    cases    discernible    only    with    the    microscope, 
and  reveal  their  presence  only  by  the  death  or  injury 
of  their  host.     The  fungous  parasites  are  very  numer- 
ous and  exhibit  great  diversity  of  structure  and  habit. 
Some  of  them  live  only  upon  enfeebled  plants,  while 
others  attack  healthy  ones.     Some,  as  the  pea  mildew, 
grow   upon   the   surface   of   their  host,    drawing   their 
nourishment   through  the    epidermis;    others,    like   the 
peach  curl  and  oat  smut,  grow  within  the  tissues  of  the 
plant  upon  which  they  feed.     All  of  the  latter  class 

*  Cuscuta  trifolia,  C.  Epilinum 


180  Principles  of  Plant  Culture. 

send  their  fruiting   parts   to   the  surface  of   the  host 
plants  to.  disseminate  their  spores  in  the  open  air. 

The  fungi  multiply  from  extremely  minute  spores 
(52)  that  are  produced  in  immense  numbers,  and  when 
mature,  are  very  readily  blown  about  by  wind.  Many 
of  them  also  multiply  from  thread-like  organs  called 
liypliae  (hy'-phas),  something  in  the  same  mariner  as 
Canada  thistles  multiply  from  their  roots. 

322.  Methods   of  Controlling    Fungi    are  of    three 
classes : 

a— Removing  and  destroying  the  affected  parts; 
b— Preventing  the  germination  of  the  spores; 
c— Destroying  the   fungus   itself  by    applying   some 
destructive  material  (a  fungicide   (fun'-gi-cide) ). 

323.  Destruction  of  the  Affected  Parts  is  the  most 
effectual  preventive  known  in  cases  where  the  fungous 
disease  attacks  a  portion  of  the  plant  whence  it  spreads 
to  the  remaining  parts,   as  in  the  black  knot  of    the 
plum,*  the  blight  of  the  pear,  apple  and  quince,f  the 
red   rust   of  the  raspberry  and   blackberry,}    and   the 
corn  smut.§ 

The  affected  part  should  be  removed  as  seen  as  dis- 
covered and  burned  at  once,  to  destroy  any  spores  of 
the  fungus  it  may  contain  or  which  might  mature  later. 
It  is  generally  important  to  cut  the  diseased  branch 
some  distance  below  the  point  of  visible  infection,  as  in 
many  cases  the  mycelia  of  the  fungus  extend  farther 
than  external  appearances  indicate. 

*  Plowriffhtia  morbosa.    •    t  Mfaroccocux  ami/lovorus. 
I  Cceoma  lumina'um.  \  UMlago  Maydit. 


Plants  as  Affected  by  Fungous  Parasites.        181 

324.  Preventing    Spore    Germination     is     the    only 
known  method  by  which  we  can  combat  the  fungi  de- 
veloping   within   the    host    plant    (endophytic    (en-do- 
phyt'-ic)  fungi). 

In  fungi  that  develop  from  spores  planted  with  the 
seed,  as  the  smuts  of  the  small  grains,  spore  germina- 
tion may  be  prevented  by  treating  the  seed  with  a  solu- 
tion of  certain  chemicals  or  with  hot  water.  Of  the 
former,  formalin  is  now  most  used,  and  unquestionably 
destroys  the  spores  of  the  smut,  and  while  it  has  gen- 
erally been  found  to  injure  more  or  less  the  germina- 
tion of  the  seed,  it  is  now  recognized  as  the  most  effi- 
cient and  practical  method  of  treating  seed  for  the 
prevention  of  smut  in  wheat,  oats  and  barley. 

325.  The    Formalin    (formaldehyd)    Treatment   con- 
sists in  immersing  the  seed  in  a  solution  of  formalin 
in   water.     To   treat  seed   oats   for   the   prevention   of 
smut  prepare  a  solution  of  one  pound  (pint)   of  forty 
per  cent  formaldehyd   (formalin)    in  thirty-six  gallons 
of  water.     The  seed  should  be  submerged  in  this  solu- 
tion for  ten  minutes  and  then  spread  on  a  canvas  or 
floor  to  dry. 

For  the  treatment  of  barley  seed  for  the  prevention 
of  smut  use  one  pint  of  formalin  in  twenty  gallons  of 
water. 

326.  Fungi    that    Develop    from    Spores    Surviving 
the  Winter  In  or  Upon  the  Soil,  as  the  onion*  smut, 
cannot  be  prevented  by  disinfecting  the  seed.     For  this 
disease  a  mixture  of  flowers  of  sulfur  and  air-slaked 


irocystis  Cepulce. 


182 


Principles  of  Plant  Culture. 


lime,  sown  with  the  seed,  has  proved  beneficial  by  pre- 
venting infection  of  the  young  plant. 

327.  Fungi  the  Spores  of  which  Survive  the  Winter 
Within  their  Dead-Host  Plants,  as  in  the  club-root  of 
the  cabbage*  and  turnip,  and  the  onion  mildew,f  may 
be  held  in  check  to  some  extent  by  burning  the  fungus- 
killed  plants  at  the  close  of  the  season. 

328.  Fungi    that    Infect    their    Host    from    Spores 
Deposited   On  the  Aerial   Parts   of  the  plant,  as  the 
scab  of  the  applet  and  pear,  and  the  downy  grape-vine 
mildew§  may  be  held  in  check  by  applying  a  fungicide 
(321)   to  the  host  plant,  to  destroy  the  spores  as  they 


FIG.   78.     A  scab  spot  mag- 
nified.    (After    Trelease.) 


FIG.  77.  Apple  affected  with 
scab  (the  dark  spots),  Fusicla- 
dium  dendriticum.  (After  Scrib- 
ner.) 


FIG.  79.  Section  through  a 
scab  spot,  highly  magnified. 
The  egg-shaped  parts  at  the 
right  are  the  spores.  (After 
Trelease.) 


alight  upon  it.  Various  compounds  of  copper  and  of 
sulfur  are  destructive  to  the  spores  of  fungi,  and  when 
properly  applied,  are  harmless  to  the  plant.  The  cop- 


*  Plasmidiophora  Ttrassicae. 
|  Fusiclailiuin  (ie/idri/icuni. 


t  Peronoxpora  Schleideniana. 
\  Peronospora  viticola. 


Plants  as  Affected  by  Fungous  Parasites.        183 

per  compounds  are  more  generally  satisfactory,  since 
they  have  the  greater  adhesive  power. 

329.  The  Bordeaux  Mixture,  which  consists  of  a 
compound  of  copper  sulfate  (324)  and  lime,  is  now  ex- 
tensively used  to  prevent  many  fungous  diseases  of 
this  class.  A  standard  formula  for  the  Bordeaux  mix- 
ture is : 

Dissolve  5  pounds  of  copper  sulfate  in  25  gallons  of 
water  by  suspending  it  in  a  bag  of  coarse  texture  near 
the  surface  of  the  water ;  slake  5  pounds  of  fresh  quick- 
lime in  sufficient  water  to  form  a  paste  and  dilute  to 
25  gallons.  Pour  the  two  solutions  together. 

Metal  vessels,  other  than  those  of  brass  or  copper, 
should  not  be  used. 

Prepared  by  the  above  formula,  the  Bordeaux  mix- 
ture often  contains  more  lime  than  is  needed  for  the 
chemical  action  that  occurs.  To  avoid  this  excess  of 
lime,  a  chemical  test  may  be  used,  as  follows :  Pour 
only  hall  of  the  slacked  lime  and  water  into  the  cop- 
per-sulfate  solution,  stir  well,  and  add  a  few  drops  of 
a  20  per  cent  solution  of  potassium  ferrocyanid.  If  a 
rich,  reddish-brown  color  is  produced,  add  more  lime. 
Continue  to  test  and  add  lime  until  the  reddish-brown 
color  no  longer  appears.  Then  add  a  little  more  lime, 
as  a  slight  excess  of  lime  is  desirable.  A  bright,  clean 
knife  blade  may  also  be  used  as  a  test.  If  a  slight  film 
of  copper  forms  upon  it  when  placed  in  the  mixture, 
more  lime  is  needed.  The  Bordeaux  mixture  is  prefer- 
ably strained  before  use,  and  should  be  kept  well  stirred 
during  its  application  (304).  It  may  be  applied  with 
any  good  spray  pump. 


184  Principles  of  Plant  Culture. 

The  arsenical  compounds  (283)  may  be  added  to  the 
Bordeaux  mixture,  and  thus  a  single  treatment  will 
serve  for  both  insects  and  fungi. 

330.  The  Diseases   Preventable  by  Bordeaux  Mix- 
ture  are  the  apple   and  pear  scab    (328),  the   downy 
mildew  and  black  rot*  of  the  grape,  the  earlyf   and 
late  blight$  of  the  potato,  the  gooseberry  mildew,  §  the 
leaf-blight  of  the  pear**  and  some  others. 

In  all  these  diseases,  however,  the  treatment  is  pre- 
ventive rather  than  curative.  The  first  application 
should  be  made  before  the  disease  appears  and  should 
be  followed  occasionally  by  others  as  new  foliage  is 
formed  or  as  the  material  is  washed  off  by  rains. 

331.  Ammoniacal    Solution    of    Copper    Carbonate 
possesses  nearly  the  same  fungicidal  properties  as  Bor- 
deaux  mixture,    but   adheres   less  strongly   to   foliage. 
Being  a  solution,  it  requires  no  straining  or  stirring, 
and  it  leaves  less  stain  on  drying  than  Bordeaux  mix- 
ture, which  makes  it  preferable  to  the  latter  for  use 
upon  plants  of  which  the  fruit  is  nearly  mature.     To 
make  this  solution,  dissolve  one  and  one-half  ounces  of 
precipitated  copper  carbonate  in  one  quart  of  strong 
commercial   ammonia,    and    add   25    gallons   of   water. 
The  ammonia  should  be  procured  in  a  glass  or  earthen 
vessel,   which  should  be  kept  tightly  corked.     To  pre- 
vent waste  of  the  ammonia  by  evaporation,  prepare  im- 
mediately before  spraying. 

332.  Potassium-Sulfid  Solution  is  used  to  some  ex- 
tent to  prevent  gooseberry  mildew    (330),   and  a  few 

*  Lee stadia  Bidwellii.    t  Macrosporium  Solani .    }  Phytophthora  i nfestans, 
I  Sphoerotheca  Mors-uvce.        **  Entomosporium  maculatum. 


Plants  as  Affected  by  Fungous  Parasites.        185 

other  diseases,  but  it  is  less  enduring  in  its  effects  than 
the  copper  compounds.  To  prepare  it,  dissolve  one- 
half  ounce  of  potassium  sulfid  (sulfuret  of  potassium, 
liver  of  sulfur)  in  one  gallon  of  water  and  apply  im- 
mediately. The  sulfid  is  best  dissolved  in  a  little  warm 
water  and  then  diluted. 

333.  Moisture   Favors  Spore  Germination,  hence  a 
free  circulation  of  air  through  the  orchard  and  vine- 
yard tends  to   prevent   fungous   diseases  by  absorbing 
excessive  moisture  (226).  Branches  of  fruit  trees  should 
not  be  permitted  to  hang  near  the  ground,  and  weeds 
should  be  kept  down. 

Grapes  are  sometimes  inclosed  in  paper  bags  on  the 
vine,  to  keep  them  dry,  and  thus  preserve  them  from 
fungous  attack.  Grape  vines  sheltered  from  rains  by  a 
cornice  are  seldom  much  troubled  with  fungous  diseases. 

334.  Fungi  that  Develop  chiefly  on  the  Outside  of 
the  Plant    (epiphytic    (ep-i-phyt'-ic)    fungi),  are  as  a 
rule  readily  controlled  by  sulfur,  either  in  the  form  of 
flowers  of  sulfur,  or  the  solution  of  potassium  sulfid 
(332).     To  this  class  belong  the  powdery  mildews  of 
the  grape,*  apple,f  etc. 

335.  The  Cultivator  will  often  Need  to  Consult  the 
Specialist  in  dealing  with  fungous  diseases.     In  many 
cases,  it  will  be  difficult  or  impossible  for  him  to  decide 
as  to  the  exact  nature  of  a  given  trouble  without  train- 
ing and  skill  in  the  use  of  the  compound  microscope. 
Specialists  in  this  line  are  now  employed  by  the  govern- 
ments of  most  civilized  nations  and  by  many  agricul- 
tural  experiment  stations,   and  they  should  be  freely 

*  Uncinula  spiralis.       f  Podosphcera  oxycanthce. 
13 


186  Principles  of  Plant  Culture. 

consulted.  Much  may  be  learned,  however,  by  studying 
the  best  books  on  the  subject.  The  cultivator  should 
be  able  to  recognize  the  principal  fungous  diseases. 

SECTION  VIII.     PLANTS  AS  AFFECTED  BY  WEEDS 

336.  Weeds  are  plants  of  the  higher  orders  that  per- 
sist in  growing  where  they  are  not  wanted.     They  in- 
jure the  desirable   plants  about  which  they  grow  by 
robbing  them  of  light,   moisture  and  food,  and  their 
presence  is  an  evidence  of  slovenly  culture.     The  re- 
markable vigor  and  prolificacy  possessed  by  many  weeds 
would  enable  them  to  soon  overcome  most  cultivated 
plants,  but  for    the  aid  of    the  cultivator.     As   with 
harmful  insects  and  fungi,  prompt  and  persistent  ef- 
forts are  essential  to  the  control  of  weeds  in  most  cul- 
tivated grounds. 

337.  Annual,  Biennial  and  Perennial  Weeds.    With 
reference  to  their  term  of  life,  weeds  and  other  plants 
are  divisible  into  three  classes,  viz.,  annual,  those  that 
live  but  one  season;  biennial,  those  that  live  only  two 
seasons;    and  perennial,  those   that  live   an   indefinite 
number  of  seasons.    Weeds  of  the  first  class  usually 
seed  most  abundantly,  and  hence  they  are  most  widely 
distributed  and   appear  in   cultivated   grounds  in  the 
greatest  numbers.     Those  of  the  third  class  are  com- 
monly most  tenacious  of  life  and  are  therefore  often 
most  difficult  to  control. 

338.  Annual  and  biennial  weeds,  since  they  have  a 
definite  life  period  and  multiply  almost  exclusively  by 
seed,  may  be  controlled  by  preventing  seedage.     To  ac- 
complish this  with  certainty,  the  plants  should  be  de- 


Plants  as  Affected  ~by  Weeds.  187 

stroyed  before  bloom,  as  many  species  possess  enough 
reserve  food  to  mature  seeds  sufficiently  for  germina- 
tion, if  cut  while  in  flower. 

339.  Perennial  weeds  often  multiply  by  suckers  as 
well  as  by  seeds  (Fig.  80).  Since  the  roots  or  under- 
ground stems  whence  the  suckers  grow  (114),  are  hid- 


FIG.  80.  Showing  how  plants  of  the  sow  thistle  multiply  from 
underground  stems. 

den  beneath  the  soil  and  are  often  extremely  tenacious 
of  life,  weeds  of  this  class  are  frequently  very  hard  to 
eradicate.  Persistent  prevention  of  leafage,  by  starv- 
ing the  protoplasm  of  the  roots,  is  always  effectual, 
though  it  is  often  very  difficult  to  carry  out,  since  the 
suckers  of  some  species  grow  with  great  rapidity.  Yet, 
on  the  whole,  no  better  remedy  is  known.  Frequent 
plowing  and  cultivation  of  the  infested  ground  is  usu- 
ally the  most  effectual  means  of  preventing  leafage. 

Certain  very  tenacious  perennial  weeds,  as  the  Can- 
ada thistle*  and  the  sow  thistle,f  when  growing  on 
deep,  rich  loams  in  which  the  roots  spread  freely  below 
the  plow  line,  may,  it  is  said,  be  crowded  out  by  seed- 
ing the  land  to  grass,  at  less  cost  than  they  can  be 
subdued  by  the  plow. 

*  Onieus  arvenns.        f  Sonchus  arvnsis. 


188  Principles  of  Plant  Culture. 

If  we  have  mastered  the  foregoing  chapters,  we  are 
now  prepared  to  enter  upon  a  more  advanced  stage  of 
culture,  and  to  learn  how  to  cause  new  plants  to  grow, 
and  how  to  treat  the  plants  thus  grown  that  they  may 
best  serve  our  purpose. 


The  following  books  are  recommended  for  reading 
in  connection  with  the  preceding  chapter:  Elementary 
Meteorology,  Waldo;  Chemistry  of  the  Farm,  Waring- 
ton;  The  Spraying  of  Plants,  Lodeman;  Economic  En- 
tomology, Smith;  Fungous  Diseases  of  the  Grape  and 
Other  Plants,  Lamson-Scribner ;  American  Weeds  and 
Useful  Plants,  Darlington. 


CHAPTER  IV. 

PLANT    MANIPULATION. 

SECTION  I.     PLANT  PROPAGATION. 

340.  Propagation,  as  the  term  is  generally  used  in 
plant  culture,  is  the  artificial  multiplication  of  plants, 
i.  e.,  reproduction   (16)   encouraged  or  induced  by  the 
knowledge,  skill  and  care  of  the  cultivator. 

Theoretically,  any  part  of  a  plant  containing  living 
cells,  with  sufficient  prepared  food  or  tissue  capable 
of  preparing  food  (58)  may  under  proper  conditions 
develop  into  a  complete  plant.  But  in  practice,  we  have 
not  been  able  to  fully  demonstrate  this  theory;  for  ex- 
ample, the  roots  and  leaves  of  some  plants  have  not 
been  induced  to  form  buds. 

341.  Plants  are  Propagated  by  Numerous  Methods, 
but  only  two  of  these  are  distinct  in  kind,  viz.,  by  seeds 
(or  spores),  and  by  division  of  the  plant.     In  propaga- 
tion by  seeds,  the  embryo  of  the  seed  (53)   is  the  vital 
center  whence  the  new  plant  is  developed.     In  propa- 
gation by  division,  a  living  bud  (127)  from  the  parent 
plant,  or  a  bit  of  tissue  capable  of  forming  a  bud,  is 
substituted  for  the  embryo  of  the  seed.     In  seed  propa- 
gation,   the   resulting   plant   is   the   product   of   sexual 
fecundation   (149),  and  hence  cannot  be  considered  as 
strictly  a  part  of  the  parent  only.     It  does  not  necessar- 
ily resemble  the  parent  closely.     In  propagation  by  di- 
vision, on  the  other  hand,  the  resulting  plant  may  be 


190  Principles  of  Plant  Culture. 

regarded  as  simply  a  continuation  of  the  growth  of  the 
parent  in  a  new  location,  and  generally  closely  resem- 
bles the  parent. 

342.  Propagation   by  Seeds   is   commonly   practiced 
with  annual  and  biennial  plants  and  with  perennials  in 
which  the  reproduction  of  the  exact  parental  form  is 
unimportant,  as  in  the  cereals,  forest  trees  and  seedlings 
intended  for  grafting.     This  method  is  also  used  when 
variation  in  the  progeny  is  desired,  as  in  developing 
new  varieties  (438  b). 

343.  Propagation  by    Division  of  the  plant  is  used 
when  it  is  desired  to  reproduce  the  exact  parental  form, 
as  in  fruit-  and  the  finer  ornamental  trees,  many  flower- 
ing plants,  etc. ;  in  certain  plants  that  are'  more  readily 
multiplied  by  division  than  by  seeds,  as  mint  and  many 
other  perennial  herbs;  and  in  other  plants  that  rarely 
or  never  produce  seed,  as  the  horse-radish,  sugar  cane, 
banana,  etc. 

A  —  PROPAGATION  BY  SEEDS. 

344.  This  is  the  most  common  method  of  propagating 
plants.     It  seemed  appropriate  to  give  nearly  all  of  the 
needed  directions  for  planting  seeds  in  the  first  two  sec- 
tions of  Chapter  II.     We  add,  therefore,  only  a  few 
general  rules  deduced  from  the  principles  there  stated. 

a — The  soil  in  which  the  seeds  are  to  be  planted  should 
be  thoroughly  crumbled,  because  the  seeds  must  have 
access  to  the  oxygen  of  the  air,  or  they  cannot  germi- 
nate (31). 

b— The  well-crumbled  soil  should  be  compactly  pressed 
about  the  seeds,  because  the  seeds  cannot  absorb  moist- 


Propagation  by  Division.  191 

ure  rapidly  unless  the  seed-case  is  in  contact  with  the 
moist  soil  particles  at  many  points  (27  b). 

c — The  soil  should  be  moist,  but  not  wet  enough  to 
puddle  (31)  ;  otherwise  the  oxygen  is  likely  to  be  shut 
out  from  access  to  the  seeds  (34). 

d — Seeds  should  be  planted  no  deeper  than  is  neces- 
sary to  insure  the  proper  degree  of  moisture;  otherwise 
the  plantlet  expends  a  needless  amount  of  energy  in 
reaching  the  surface  (50,  47).  Very  small  seeds  should 
be  only  slightly  covered,  if  at  all,  and  must  receive  ar- 
tificial watering  when  necessary  (51).  Spores  must  not 
be  covered  with  soil  at  all  (52). 

B  —  PROPAGATION  BY  DIVISION. 

345.  We  have  seen  that  a  part  of  a  plant,  placed  un- 
der favorable  conditions,  is  usually  capable  of  develop- 
ing a  complete  plant  (340).  A  section  or  cutting  of 
the  stem,  for  example,  that  has  no  roots  at  the  time  it 
is  cut  off,  may  be  caused  to  form  roots,  and  thus  be- 
come a  complete  plant.  A  cutting  of  a  root  may  also 
put  forth  a  bud,  which  in  turn  may  develop  into  a 
shoot,  and  form  leaves,  flowers  and  fruit.  Again,  we 
have  seen  that  portions  of  cambium  from  different, 
nearly-related  plants  may  unite  by  growth  (69),  which 
enables  us  to  change  undesirable  sorts  into  valuable 
ones  by  grafting  (383).  These  and  certain  other  meth- 
ods of  multiplying  plants,  come  under  propagation  by 
division. 

In  propagation  by  division,  the  presence  of  at  least 
one  healthy  growing  point  (66)  in  the  part  selected  for 
the  propagation  is  generally  essential  to  success  and  is 
always  helpful. 


192  Principles  of  Plant  Culture. 

The  processes  treated  in  this  and  the  two  succeeding 
sections  may  be  likened  to  surgical  operations  in  medi- 
cine. If  plants  are  less  highly  organized  and  possess 
less  of  sensibility  than  the  higher  animals,  they  are, 
none  the  less,  living  beings.  Violent  operations,  if  nec- 
essary, should  always  be  performed  with  this  truth  in 
mind.  Needless  injury  and  careless  handling  in  tin- 
treatment  of  plants  are  always  to  be  avoided. 

346.  Two  Methods  of  Propagation  by  Division  may 
be  distinguished,  viz.,  by  parts  intact  and  detached 
parts.  In  the  first,  the  part  selected  for  propagation  is 
not  separated  from  the  parent  until  the  organs  needed 
to  make  it  self-supporting  are  formed;  or  if  a  cion 
(386),  until  it  has  united  to  the  part  on  which  it  is  in- 
tended to  grow.  In  the  second  method,  the  part  in- 
tended for  propagation  is  severed  from  the  parent  at 
the  outset  and  placed  under  conditions  favoring  the  for- 
mation of  the  organs  needed  to  make  it  self-supporting ; 
or  if  a  cion,  favoring  its  union  with  the  stock  (383). 

A— PROPAGATION  BY  PARTS  INTACT. 

This  method  is  applicable  to  many  plants  and  has  the 
advantages  of  being  reliable  and  requiring  little  skill. 
The  part  selected  for  propagation,  being  nourished  by 
the  parent  until  it  forms  the  needful  organs,  is  able  to 
endure  unfavorable  conditions  that  would  prove  fatal 
in  most  other  methods  of  propagation.  This  method  in- 
cludes four  divisions,  viz.,  propagation  by  suckers 
(347),  by  stolons  (348),  by  layers  (349),  and  by  ap- 
proach grafting  (399).  In  the  first  two,  the  propaga- 
tion is  performed  by  the  parent  plant  without  other 


Propagation  ~by  Parts  Intact. 


193 


aid  than  the  maintenance  of  a  well-aerated,  moist  and 
clean  soil  that  stimulates  the  production  of  the  needed 
organs,  which  in  these  cases  are  roots. 

347.  Propagation  by  Suckers.  Suckers  are  shoots 
that  originate  from  roots  or  underground  stems  and 
grow  upward,  forming  young  plants  about  the  parent, 
as  in  the  blackberry,  plum,  choke-cherry,  etc.  The  propa- 
gation consists  in  simply  cutting  off  the  root  or  under- 
ground stem  whence  the  sucker  proceeds,  and  trans- 
planting the  latter. 

The  growth  of  suckers  may  generally  be  stimulated  in 
plants  that  naturally  produce  them,  by  cutting  off  the 
roots  or  underground  stems  from  which  they  grow,  or 
by  severely  pruning  the  top. 

The  propagation  of  woody  plants  from  suckers  is  not, 
as  a  rule,  considered  wise,  since  the  roots  are  usually 
poorly  developed  in  proportion  to  the  stem,  and  some 


FIG.   81.  FIG.   82. 

FIG.  81.     Sucker   plant   of    the   red    raspberry.    Rubus   strigosus. 
A,    before    growth    has    strated;    B,    after.     The    two    shoots    of    B 


starting  just  above   the  roots   form    the  new   canes. 

FIG.  82.     Tip    plant    of  black   rasp 
young    shoot    starts,    appears    at    th< 


berry.     The   bud,    whence    the 
base    of    the    present    cane. 


plants  grown  in  this  manner  seem  to  acquire  the  ten- 
dency to   form  suckers  excessively.     In  the  red  rasp- 


194  Principles  of  Plant  Culture. 

berry*  and  the  blackberry,f  however,  propagation  by 
suckers  is  the  most  convenient  method,  and  it  appears 
to  be  followed  by  no  bad  results  (Fig.  81). 

348.  Propagation  by  Stolons.  A  stolon  is  a  branch 
that  starts  above  or  at  the  surface  of  the  ground  and 
either  grows  prostrate  or  curves  downward  till  it  reaches 
the  ground  where  it  takes  root,  usually  at  the  nodes 
(115).  The  currant,  juneberry,  cranberry  and  many 
herbaceous  plants  are  readily  multiplied  in  this  way. 
Stolons  often  root  without  assistance,  but  the  rooting  is 
much  hastened  and  encouraged  by  covering  the  branch 
with  soil.  When  well  rooted,  the  young  plants  may  be 
separated  from  the  parent  by  cutting  the  stolons. 

Woody  plants  grown  from  stolons  are  seldom  uniform 
in  size  and  are  not  often  as  well  rooted  as  those  grown 
from  cuttings  (358).  Some  herbaceous  plants  are,  how- 
ever, more  readily  propagated  by  stolons  than  by  any 
other  means. 

The  offset  by  which  the  houseleekj  is  so  readily  prop- 
agated, is  a  very  short  stolon  that  forms  a  single  tuft  of 

leaves     at     its     apex. 
The  cane  of  the  black- 
cap raspberry,  §   which 
roots  from  the  tip  (Fig. 
82),    and   the   runner 
of       the       strawberry 
(Fig.  83),  that  forms 
FIG.  83.    Runner  of  the  strawberry,     a  plant  at  each  alter- 
nate node,  are  modified  stolons. 


*Rubus  striffosus,  R.  Idceus.         f  JR.  villosus. 
ISempervivum.  QRubus  occidentalis. 


Propagation  by  Parts  Intact.  195 

349.  Propagation     by     Layers     or     Layering.     The 

layer  is  an  artificial  stolon,  i.  e.,  a  branch  that  does  not 
naturally  grow  downward,  which  is  covered  with  or 
surrounded  by  moist  soil  to  stimulate  the  production  of 
roots  (88).  The  branch  may  be  bent  down  and  cov- 
ered, as  is  usally  practiced  with  the  grape,  wistaria, 
etc.,  or  the  soil  may  be  ridged  up  about  the  branch,  as 
is  done  with  the  quince  and  paradise  apple.  In  either 
case,  the  terminal  portion  of 
the  stem  is  commonly  left 

unc.°vered-    In   the   latter 
method;  whieh  is  known  as 

mound-layering,    (Fig.    84), 

^  .t- the  stems  of  the  plant  to  be 

-  "  ""          layered   are   usually   cut  off 

FIG.     84.      Mound-layering     of   just     above     the     surface    of 
gooseberry    plants.    (After    Bai-  . 

ley.)  the  ground  in  early  spring, 

to  stimulate  the  formation  of  vigorous  shoots,  which 
are  ridged  up  about  midsummer  or  preferably  not  until 
the  succeeding  fall  or  spring.  The  ridging  should  be 
sufficiently  high  to  cover  several  .of  the  lower  nodes 
(115).  Roots  grow  out  at  the  nodes  and  the  shoots  are 
usually  well  rooted  by  the  autumn  following  the  ridging. 
Many  woody  plants  that  do  not  readily  form  roots 
when  layered,  may  be  induced  to  do  so  by  mutilating 
the  stem  somewhat  in  the  covered  part.  This  tends  to 
restrict  the  growth  current  (79)  and  causes  an  accu- 
mulation of  reserve  food,  from  which  roots  may  grow. 
Girdling,  twisting,  bending  or  splitting  the  stem  for  a 
short  distance  will  often  have  the  desired  effect 
(Fig.  85). 


196  Principles  of  Plant  Culture. 

Layering  is  a  very  reliable  and  expeditions  method  of 
propagating  many  woody  and  herbaceous  plants. 

350.  Propagation  by  Division  of  the  Crown  of  the 
plant,  which  is  practicable  with  many  perennial  herbs, 

as  the  rhubarb,  dahlia,  globe  artichoke,  etc., 
though  not  strictly  analogous  to  propagation 
by  stolons  or  layers, 
may  be  considered 
here.  It  consists  in 
taking  up  the  plant, 
preferably  while  dor- 
mant, and  cutting  the 
crown  into  two  or 
more  parts,  according 
to  its  size  or  the  num- 

FIG.  85.  Layered  branch  of  cur-  her  of  plants  desired, 
rant,  split  to  encourage  the  forma- 

tion  of  roots.  an(j  planting  the  divi- 

sions as  separate  plants.  This  method  is  applicable  to 
propagation  for  private  use,  rather  than  for  sale  pur- 
poses. 

Propagation  by  approach  grafting,  although  in  order 
here,  is  more  readily  treated  with  the  other  methods  of 
grafting  (399). 

B — PROPAGATION  BY  DETACHED  PARTS. 

This  comprises  two  different  modes  of  propagation, 
viz.,  by  specialized  buds  and  by  sections  of  the  plant. 

a  —  Propagation  by  Specialized  Buds. 

351.  This    includes    propagation   by    bulbs,    bulblets, 
corms  and   tubers.     It  is  in  a  sense  intermediate  be- 
tween propagation  by  parts  intact   (346)    and  by  cut- 


Propagation  by  Detached  Parts. 


197 


tings  (358).  The  bud  that  is  to  form  the  future  plant, 
though  not  having  roots  of  its  own,  has  been  specially 
prepared  by  the  parent,  through  an  abundant  food 
supply  and  a  partially  dormant  condition  of  the  proto- 
plasm, to  maintain  a  separate  existence,  even  under 
adverse  conditions,  and  in  due  time  to  develop  into  a 
plant.  In  these  respects  it  resembles  a  seed,  from  which 
it  differs,  however,  in  the  less  dormant  condition  of  its 
protoplasm  and  in  not  being  the  product  of  sexual  fec- 
undation (341). 

352.  The  Bulb  is  a  very  short  stem  containing  a  ter- 
minal bud  inclosed  in  scales  (127).  The  scales  are 
thickened  by  a  store  of  food,  and  in 
their  axils  are  smaller  lateral  buds. 
The  terminal  bud  usually  develops 
into  a  flower  and  then  perishes.  One 


FIG.  86.  FIG.  87.  'Fio.  88.  FGI. 

FIG.  86.  Bulb  of  the  common  onion,  Allium  cepa,  divided 
lengthwise.  B,  buds. 

FIG.  87.  Bulb  of  garlic,  Allium  sativum.  It  contains  several 
smaller  bulbs  (cloves). 

FIG.  88.     Bulb    of   wild    lily. 

FIG.  89.     The  same   divided  lengthwise,    showing  buds,    B. 

or  more  of  the  lateral  buds  may  develop  into  flower- 
buds  for  the  next  year  and  thus  continue  the  life  of 
the  plant,  as  in  the  common  onion  (Fig.  86)  ;  or  the 
lateral  buds  may  develop  at  the  expense  of  the  parent. 
as  in  the  potato  onion. 


198 


Principles  of  Plant  Culture. 


353-  Bulblets  or  Bulbels  are  small  bulbs  formed  in 
the  axils  of  the  leaves  in  certain  plants,  as  the  tiger 

lily,*  (Fig.  90),  or 
at  the  apex  of  the 
stem,  as  in  the 
"top"  or  bulb-bear- 
ing onion  (Fig.  91). 
354.  The  Corm 
(Fie:.  92)  differs 

FIG.  90.     Bulblets   in  axils   of   leaves    of   v 

tteer  lily.  from  the  bulb  chief- 

ly  in  being  without  scales.  The  food  is  deposited  in 
the  thickened  stem.  The  corms  of  our  flowering  plants, 
as  the  crocus,  cyclamen,  etc.,  are  generally  called  bulbs 
in  commerce. 

355.  The  Tuber,  of  which  the  common  potato  is  the 
most  familiar  example,  differs  from  the  corm  in  being 
the  end  of  an  underground  branch  of 
the  stem   (114), instead 
of  developing  in  direct 
contact   with   the    par- 
ent.    It  also  has  more 
numerous   buds    (eyes) 
than  the  corm. 

356.        Propagation 

Uilbs,    Bulblets, 
following    year.         C()rms     &nd    Tubers    }s 

a  very  simple  operation  and  consists  merely  in  planting 
these  parts  in  the  place  where  the  plants  are  desired. 
Tubers  may  be  cut  into  pieces  containing  one  or  more 
buds  each,  if  desired.  The  rules  given  for  planting 
seeds  (344)  apply  equally  well  here.  All  should  be 

*  Lilium  tigrinum. 


Propagation  by  Detached  Parts.  199 

stored  for  preservation  in  a  cool,  moderately  dry  place, 
that  is  free  from  frost.  They  retain  their  vitality  but 
a  single  year. 

In  the  methods  of  propagation  thus  far  considered, 
with  the  sole  exception  of  layering  (349),  advantage 
has  been  taken  of  a  natural  mode  of  plant  multiplica- 
tion. The  skill  of  the  cultivator,  however  much  it  may 
assist  the  processes,  is  not  necessary  to  their  success, 
since  wild  plants  habitually  increase  by  the  same  meth- 
ods. We  will  now  consider  a  method  which  is  less  often 
illustrated  in  nature,  and  in  which  the  skill  and  care  of 
the  cultivator  are,  as  a  rule,  essential  to  its  accomplish- 
ment, viz: 

b  —  Propagation  by  sections  of  the  plant. 

The  various  methods  of  propagation  in  this  division 
are  alike  in  the  fact  that  a  detached  part  of  the  parent 
plant,  containing  living  protoplasm,  is  placed  for  a  time 
under  specially  favorable  conditions,  in  virtue  of  which 
the  part  is  enabled  not  only  to  live,  but  to  perform  its 
functions  and  reproduce  the  needed  organs ;  or  if  a  cion 
(386),  to  unite  by  growth  to  the  part  with  which  it  is 
placed  in  contact. 

357.  In  propagation  by  sections  of  the  plant  we  must, 
of  necessity,  wound  the  plant  tissues  in  securing  the 
parts  for  propagation.  Since  it  is  always  desirable  that 
the  wound  should  heal  promptly  (72),  it  is  important 
that  the  cutting  tools  used  should  liave  sharp  and 
smooth  edges. 

As  here  considered,  propagation  by  sections  of  the 
plant  includes  two  methods,  differing  materially  in 


200  Principles  of  Plant  Culture. 

their  requirements  and  in  the  manner  of  development 
of  the  plants,  viz.,  propagation  by  cuttings  and  by 
grafting. 

a— Propagation   ~by  Cuttings. 

358.  A  Cutting  is  a  detached  member  of  a  plant,  in- 
tended to  be  placed  in  the  soil  or  some  other  medium 
for  propagation.     It  may  be  in  an  active  or  a  dormant 
state    (13),  and  may  or  may  not  contain   a  growing 
point  (66).     Before  the  cutting  can  become  a  plant,  it 
must  develop  the  essential  part  or  parts  of  the  plant 
that  it  lacks;  i.  e.,  the  stem  and  the  leaves,  or  the  root, 
or  all  these  members.     Cuttings  of  the  stem  are  usually 
planted  with  their  proximal  end  (115)  in  the  soil,  and 
their  distal  end  in  the  air.     Root  cuttings  are  generally 
covered  in  the  soil. 

359.  Nearly  All  Plants  may  be  Propagated  by  Cut- 
tings  from  one  or  another  of  their  parts.     The  ease 
with  which  plants  may  be  multiplied  in  this  way  varies 
greatly  in  different  species  (21),  and  even  in  different 
varieties   of  the   same   species.     The   appearance   of   a 
plant  does  not  always  indicate  the  facility  with  which 
it  may  be  grown  from  cuttings;  the  only  sure  way  to 
ascertain  this  is  by  trial. 

Climate  exerts  a  marked  influence  upon  the  tendency 
of  plants  to  develop  from  cuttings.  In  certain  loca- 
tions in  southern  Europe  and  in  parts  of  South  Amer- 
ica, branches  of  the  common  apple  tree,  sharpened  and 
driven  into  the  ground  as  stakes,  often  take  root  and 
sometimes  even  bear  fruit  during  the  same  season.  A 


Propagation  by  Cuttings.  201 

warm,  moist  atmosphere  is  very  favorable  to  propaga- 
tion by  cuttings. 

We  have  seen  that  the  roots  of  certain  plants  nor- 
mally develop  buds  (130).  In  like  manner,  the  stems 
of  many  plants,  as  the  potato,  grape,  etc.,  normally 
develop  growing  points  of  roots  at  their  nodes  (115). 
Plants  that  normally  develop  buds  upon  their  roots, 
or  growing-points  of  roots  at  their  nodes,  are  readily 
propagated  by  cuttings.  But  propagation  by  cuttings 
is  not  limited  to  such  plants  (362). 

360.  The    Essential    Characteristics    of    a    Cutting 
are  a — a  certain  amount  of  healthy  tissue;  &— a  certain 
amount  of  prepared  food,  or  of  tissue  capable  of  pre- 
paring food  (58)  ;  c — in  most  species,  a  growing  point 
(66),  either  of  the  stem  or  root,  or  of  both. 

361.  The  Parts  of  plants  to  be  Used  for  Cuttings, 
therefore,  are  preferably  the  younger,  matured  growths, 
since  the  tissues  of  these  are  most  vigorous;  or  else  a 
part  that  possesses   a  certain   amount  of  healthy   and 
vigorous  leaf  tissue.     The  cutting  should  always   con- 
tain one  or  more  buds  when  practicable   (127). 

362.  Conditions  that  Favor  the  Growth  of  Cuttings. 
a— A  soil  warmer  than   the   air  above   it    ("bottom 

heat")  is  important  in  growing  many  plants  from  cut- 
tings. Warmth  stimulates  plant  growth,  and  when  ap- 
plied to  one  part  of  a  plant,  it  stimulates  growth  in 
that  part.  If  the  soil  about  a  planted  cutting  is  warmed 
to  a  temperature  considerably  higher  than  that  of  the 
air  above,  the  growth  of  roots  is  stimulated.  Indeed 
bottom  heat  often  excites  growth  in  cuttings  that  will 
not  grow  without  it. 

14 


202  Principles  of  Plant  Culture. 

b — A  comparatively  low  air  temperature  is  import- 
ant in  growing  many  plants  from  cuttings  of  the  stein 
(377),  because  it  is  essential  that  the  stem  growth  be 
held  in  check  until  roots  are  formed.  A  soil  tempera- 
ture of  about  65°  F.,  with  an  air  temperature  about 
fifteen  degrees  lower,  is  suited  to  the  great  majority  of 
plants  usually  propagated  under  glass  from  cuttings. 
It  is  important  that  these  temperatures  be  maintained, 
nearly  constant  until  roots  have  developed. 

Since  we  have  better  facilities  for  raising  than  for 
lowering  the  natural  temperature  of  the  atmosphere, 
propagation  from  cuttings  is  easiest  at  a  time  of  the 
year  when  the  temperature  of  the  atmosphere  during 
the  day  does  not  much  exceed  50°.  By  observing  spe- 
cial precautions,  however,  it  is  possible  to  propagate 
many  plants  from  cuttings  during  the  warm  season. 

a— Abundant  moisture  is  important  in  growing  plants 
from  cuttings,  because  moisture  favors  root  develop- 
ment (88),  and  water  is  essential  to  cell  growth  (62). 
The  amount  of  water  required  varies  considerably  with 
different  plants  and  conditions. 

With  cuttings  containing  leaf  tissue  (377,  382), 
transpiration  (74)  must  be  reduced  to  the  minimum 
until  roots  are  formed,  because  water  cannot  be  taken 
up  freely  without  root-hairs  (100).  For  such  cuttings, 
therefore,  the  air  as  well  as  the  soil  must  be  kept 
abundantly  moist  (369),  and  the  direct  rays  of  the  sun 
must  be  intercepted  by  shading  (235). 

363.  Methods  for  Controlling  Temperature.  The 
alternations  of  temperature  in  the  open  air  are  un- 
favorable to  the  development  of  cuttings,  though  many 


Propagation  by  Cuttings.  203 

plants,  as  the  willow,  grape  and  currant,  are  readily 
propagated  from  cuttings  out  of  doors.  Some  struc- 
ture, therefore,  that  may  confine  warmth  radiated  from 
the  earth  or  artificially  generated,  or  that  may  when 
necessary  shut  out  a  part  of  the  solar  heat,  is  always  of 

great  assistance 
i  n  propagating 
plants  from  cut- 
tings, and  in 
many  species  is 
essential  to  suc- 

FIG.  93.     Cold-frame,    with    sash    lifted    for  o.  v    ,  , 

ventilation.  C6SS.     Since  light 

is  necessary  to  food  preparation  (58),  such  a  structure 
must  be  roofed  with  glass  or  some  other  more  or  less 
transparent  material. 

364.  The  Cold-Frame  (Fig.  93)  is  the  simplest  struc- 
ture of  this  kind.  It  consists  of  a  frame  or  box  with- 
out bottom,  usually  shallower  on  one  side  than  on  the 
other,  covered  with  glazed  window  sash.*  The  frame 
is  generally  placed  so  that  its  shallower  side  faces  the 
south,  thus  giving  its  cover  a  southward  slope.  It  has 
no  provision  for  artificial  heat,  though  when  covered 
with  glass,  the  temperature  within  the  frame  is  much 
increased  during  sunshine,  owing  to  the  property  pos- 
sessed by  glass  for  confining,  the  heat  rays.  The  cold- 
frame  should  be  protected  in  freezing  weather  by  an 
additional  cover  of  mats  or  blankets,  while  excessive 
sun  heat  should  be  avoided  by  shading  (235).  Muslin- 
or  paper-covered  frames  require  no  shading. 

*  Muslin  or  paper  is  sometimes  used  instead  of  glass,  and  these 
materials  may  be  rendered  waterproof  and  less  opaque  by  paint- 
ing with  linseed  oil  or  some  similar  material. 


204 


Principles  of  Plant  Culture. 


Although  affording  no  bottom  heat  (362  a),  the  cold- 
frame  may  be  used  for  propagating  many  plants  from 
cuttings.  It  is  also  serviceable  in  connection  with  the 
propagating  bed  (368)  for  "hardening  off"  young 
plants  grown  from  cuttings  in  the  latter,  as  well  as  for 
growing  many  plants  from  seed.  Set  over  a  pit  in  the 
earth,  the  cold-frame  makes  an  excellent  place  (cold 
pit)  for  wintering  half-hardy  plants. 

365.  The  Hotbed  differs  from  the  cold-frame  in  hav- 
ing bottom  heat  (362  a),  which  is  usually  supplied  by 
the  fermentation  of  moist  vegetable  material,  as  horse 
manure,  leaves,  refuse  hops  or  tan  bark.  The  material 
intended  for  heating,  if  fresh,  should  be  thrown  into 
a  pile  of  sufficient  size  to  generate  heat  several  days 
before  it  is  desired  for  use ;  and  unless  already  moist, 
it  should  be  moderately  sprinkled  with  water.  In  or- 
der that  all  the  material  may  reach  the  same  stage  of 
fermentation,  the  mass  should  be  made  into  a  new  pile 
after  the  heating  starts  vigorously,  as  is  indicated  by 

vapor  rising 
from  the  heap, 
and  the  outer 
part  of  the  mass 
should  be  placed 
in  the  center  of 
the  new  pile, 

FIG.  94.     Cross -section  of  hotbed   in  pit.  The  Leaves    ferment 
frame  is  banked  up  a  little  with  earth.    (After 

Qreiner.)  slower  than  the 

other  materials  above  named,  and  hence  may  often  be 
advantageously  mixed  with  them  to  lengthen  the  period 
of  fermentation. 


Propagation  ~by  Cuttings.  205 

Heat  is  economized  by  placing  the  fermenting  mate- 
rial in  a  pit  in  the  ground,  but  hotbeds  are  often  made 
above  ground.  The  hotbed  pit  should  be  in  a  well- 
drained  and  sheltered  place,  and  two  to  two  and  one- 
half  feet  deep.  In  this  the  heating  material  shuuld  be 
moderately  packed,  until  the  pit  is  nearly  or  quite  full. 
The  frame  may  then  be  placed  over  the  pit,  after  which 
the  heating  material  should  be  covered  with  soil  and 
the  sash  put  on  to  confine  the  warmth.  Within  a  few 
days  after  covering  with  the  sash,  the  fermenting  mate- 
rial usually  generates  a  rather  violent  heat,  which 
should  be  permitted  to  decline  to  about  90°  F.,  before 
planting  seeds  or  cuttings  in  the  hotbed.  The  same 
protection  against  excessive  heat  or  cold  is  used  as  for 
the  cold-frame ;  but  the  hotbed  requires  much  more  care 
in  ventilation,  since  the  heating  material  generates 
vapor  and  carbonic  acid  as  well  as  heat,  and  these  when 
present  in  excess  are  detrimental  to  plant  growth. 

366.  The  Greenhouse  is  an  expansion  of  the  hotbed, 
i.  e.,  a  structure  sufficiently  large  so  that  it  may  be  en- 
tered, and  arranged  for  heating  by  fire.*  In  temperate 
climates,  greenhouses  are  usually  constructed  12  to  22 
feet  wide,  with  a  gable  or  M  roof,  having  a  slope  of  35° 
to  40°,  covered  with  glass  and  with  the  ridge  or  ridges 
extending  north  and  south  (Fig.  95)  ;  but  in  very  cold 
climates  a  shed  roof  facing  the  south  is  preferable. 
Greenhouses  are  often  built  with  one  slope  of  the  roof 
longer  and  less  steep  than  the  other,  and  with  the  ridge 
extending  east  and  west.  Such  a  roof  is  called  a  "two- 
thirds"  or  "three-quarters  span,"  according  as  the 

*  Hotbeds  are  now  being  heated  by  fire  to  some  extent. 


206 


Principles  of  Plant  Culture. 


longer  slope  covers  two-thirds  or  three-quarters  of  the 
width  of  the  house.  The  long  slope  usually  faces  the 
south,  but  houses  have  recently  been  built  with  the 
shorter  and  steeper  slope  facing  the  south,  a  plan 
thought  to  possess  advantages  for  growing  certain 
plants,  as  carnations. 

Provision  is  made  for  ventilation  in  glass  houses  by 
placing  a  certain  number  of  movable  sash  in  the  roof  or 
elsewhere.  In  order  that  the  glass  may  not  be  far  above 
the  plants,  the  side  walls  should  not  exceed  five  feet  in 
height  (240).  These  may  be  of  wood,  but  a  wall  of 
brick,  ten  inches  thick,  with  a  two-inch  air  space  in  the 


FIG.  95.     Cross-section    of    greenhouse.      (After   Grelner.) 

center,  is  preferable,  since  this  better  economizes  heat. 
The  furnace  and  potting  rooms  obstruct  the  light  least, 
and  afford  the  most  protection,  when  located  to  form 
the  wall  opposite  to  the  sun.  In  houses  extending  north 
and  south,  the  south  end  is  usually  glazed  above  the 
height  of  the  side  walls. 

367.  Heating  Devices  for  the  Greenhouse  are  of 
various  kinds.  The  "smoke  flue"  is  simplest  and  cheap- 
est in  first  cost.  It  consists  of  a  flue  extending  from  the 
furnace,  which  is  placed  somewhat  below  the  floor  level, 
lengthwise  through  the  house,  preferably  rising  gradu- 
ally to  a  chimney  at  the  opposite  end;  or  the  flue  may 


Propagation  by  Cuttings.  207 

cross  the  farther  end  of  the  house  and  return  at  the 
other  side,  to  a  chimney  built  directly  upon  the  furnace. 
The  latter  method  usually  gives  better  draft,  since  the 
warmth  from  the  furnace  stimulates  an  upward  current 
of  air  through  the  chimney.  The  flue  should  be  of  brick 
for  the  first  25  feet  from  the  furnace,  as  a  safeguard 
from  fire.  After  this  it  may  be  of  cement,  or  of  vitri- 
fied drain-pipe. 

Greenhouses  of  the  better  class  are  now  almost  in- 
variably heated  with  steam  or  hot  water,  or  with  a  com- 
bination of  the  two.  Pipes  from  a  boiler  located  be- 
neath the  floor  level,  extend  nearly  horizontally  about 
the  house,  below  the  benches,  returning  to  the  boiler ;  or 
the  main  feed  pipe  extends  overhead  to  the  farther  end 
of  the  house,  where  it  connects  with  a  system  of  return 
pipes  beneath  the  benches.  While  the  steam-  or  hot- 
water  heating  costs  much  more  at  the  outset  than  the 
smoke-flue  system,*  it  is  generally  found  not  less  eco- 
nomical and  far  more  satisfactory  in  the  long  run. 
Where  the  pipes  need  to  make  many  turns,  steam  is 
usually  more  satisfactory  than  hot  water. 

368.  The  Propagating  Bed.  A  certain  part  of  the 
greenhouse  is  usually  set  apart  for  propagating  plants 
from  cuttings.  The  propagating  bed  is  made  upon  the 
ordinary  greenhouse  bench,  directly  over  the  flue  or 
heating  pipes.  To  furnish  the  bottom  heat  (362  a),  the 
space  beneath  the  bench  is  boxed  in  with  boards.  Hori- 
zontal doors  are,  however,  provided  which  may  be 

*  In  round  numbers,  the  cost  of  the  smoke-flue  may  be  esti- 
mated at  ten  per  cent  of  the  whole  outlay  required  In  a  house 
heated  by  this  method,  while  in  one  heated  with  hot  water  or 
steam,  the  cost  of  the  heating  apparatus  Is  not  far  from  fifty 
per  cent  of  the  whole. 


208  Principles  of  Plant  Culture. 

opened  when  it  is  desirable  to  allow  a  part  of  the  heat 
to  pass  directly  into  the  house.  The  floor  of  the  bench 
should  not  be  so  tight  as  to  hinder  drainage. 

In  large  commercial  establishments,  entire  glass 
houses  are  often  devoted  solely  to  propagation.  Such 
houses  are  usually  eleven  or  twelve  feet  wide,  with  low 
side  walls.  Sometimes  lean-to  houses  are  built  for 
propagation,  on  the  north  side  of  a  wall,  where  direct 
sunlight  is  cut  off. 

In  making  the  propagating  bed,  a  thin  layer  of  sphag- 
num moss  is  usually  spread  over  the  floor  of  the  bench 
and  covered  to  a  depth  of  two  to  four  inches  with  well- 
packed,  clean,  rather  coarse  sand,  brickdust  or  pow- 
dered charcoal.  Sometimes  the  whole  bed  is  made  of 
moss.  These  materials  are  used  because  they  will  not 
retain  an  excess  of  water  if  the  proper  provision  is  made 
for  drainage.  Sand  is  mcst  used  because  it  is  as  a  rule 
readily  obtained,  but  it  needs  to  be  selected  with  care, 
as  it  often  contains  injurious  mineral  matters.  Sand 
found  along  the  borders  of  fresh-water  streams  or  lakes 
may  generally  be  used  without  washing,  but  that  dug 
from  sandpits  should  in  most  cases  be  exposed  to  the  air 
for  a  few  weeks,  and  then  be  thoroughly  washed  before 
being  employed  for  cuttings.  The  same  sand  should  be 
used  for  but  one  lot  of  cuttings,  as  a  rule,  for  it  is  liable 
to  •  become  infested  with  fungi  that  may  work  havoc 
with  cuttings  placed  in  it. 

369.  Methods  of  Controlling  Humidity.  Where 
moisture  needs  to  be  controlled  with  especial  care,  as  in 
propagating  delicate  plants  from  green  cuttings,  or  in 
herbaceous  grafting  (393),  the  planted  cuttings  or  the 


Propagation  by  Cuttings.  209 

grafted  plants  are  often  covered  with  bell-jars.  To 
guard  against  sudden  fluctuations  in  temperature,  a 
larger  bell-jar  is  sometimes  placed  over  a  smaller  one. 
By  means  of  a  bell-jar  with  a  tight- 
fitting  ground  plate,  evaporation 
may  be  wholly  prevented  from  cut- 
tings or  plants,  if  do- 
sired.  Propagating  beds 
are  often  covered  with 
glazed  sash,  in  addition 
to  the  glass  roof  of  the 
house,  to  assist  in  main- 
taining a  moist  atmos- 
phere about  the  cut- 
tings (Fig.  96). 

For  convenience,  we 
separate  propagation  by  cuttings  into  two  divisions, 
viz.,  propagation  by  cuttings  from  dormant  and  from 
active  plants.  The  requirements  of  these  two  classes 
differ  in  some  respects. 

a — Propagation  by  cuttings  from  dormant  plants. 

370.  The  Time  to  Make  the  Cuttings.  We  have 
seen  that  plant  processes  may  not  be  wholly  suspended 
during  the  dormant  period  (176).  This  is  true  not 
only  of  the  plant  as  a  whole,  but  also  of  detached  parts 
of  the  plant,  if  they  are  protected  from  evaporation. 
If  cuttings  are  taken  from  a  plant  in  autumn  and 
stored  during  winter  in  a  moist  place  of  moderate  tem- 
perature, the  cut  surfaces  will  partially  callus  over 
(72),  and  the  formation  of  roots  or  buds  may  com- 
mence before  spring. 


FIG.  96.     Propagating    bed    covered 
with  glazed  sash. 


210  Principles  of  Plant  Culture. 

When  new  growing  points  must  be  developed  before 
the  cuttings  can  form  a  plant,  as  with  cuttings  of  the 
stem  and  roots  of  many  species,  cuttings  of  dormant 
plants  are  preferably  made  at  the  beginning  of  the  dor- 
mant period,  i.  e.,  in  autumn,  and  placed  during  winter 
under  conditions  favoring  the  formation  of  new  grow- 
ing points. 

371.  The  Storage  of  Cuttings.  Cuttings  should  be 
stored  in  a  place  sufficiently  moist  to  prevent  loss  of 
water  by  evaporation,  and  warm  enough  to  favor  mod- 
erate root  growth.  Cuttings  with  ready-formed  buds 
must  be  kept  cool  enough  to  prevent  growth  of  these. 
Root  growth  may  proceed  to  some  extent  at  tempera- 
tures too  low  to  excite  the  buds.  These  conditions  are 
usually  fulfilled  by  covering  the  cuttings  in  damp  saw- 
dust, sand  or  loose  loam,  and  storing  them  through  the 
winter  in  a  moist,  moderately  cool  cellar,  or  by  bury- 
ing them  in  the  open  ground  beneath  the  frost  line.  In 
mild  climates  the  latter  plan  is  often  preferable.  Stem 
cuttings  (373)  of  plants  that  do  not  root  freely  from 
the  stem  are  frequently  buried  with  the  proximal  end 
(115)  uppermost.  This  gives  them,  to  some  extent, 
the  advantage  of  bottom  heat  (362  a),  since  the  sur- 
face layers  of  the  soil  are  first  warmed  by  the  sun  in 
spring. 

Cuttings  stored  in  the  ground  over  winter  should  be 
taken  up  and  planted  in  spring  before  the  buds  expand. 

Cuttings  of  evergreen  plants  should  not  be  buried,  as 
this  would  destroy  the  leaves,  without  which  they  rarely 
form  roots.  Cuttings  of  these  plants  are  usually  made 
in  autumn  and  planted  at  once  in  boxes  of  sand,  which 


Propagation  by   Cuttings. 


211 


are  kept  for  a  time  in  a  light,  cool  place,  as  a  cool 
greenhouse,  until  the  growing  points  of  the  roots  have 
formed,  after  which  they  are  removed  to  a 
warmer  location. 

372.  Planting    Cuttings    in    Autumn.     Stem 
cuttings  of  the  currant  and  other  hardy  plants, 
and  root  cuttings   (376)   of  the  blackberry,  are 
sometimes  made  as  soon  as  the  wood  is  mature 
in  autumn,  and  planted  at  once  in  well-drained 
loamy  or  sandy  soil  in  the  open  ground. 
Cuttings  thus  treated  often  commence  to 
form  roots  before  winter.     They  should  be 
covered  with  a  little  earth   and  mulched 
with  some  coarse  litter  on  the  approach  of 
freezing  weather,  and  should 
be   shaded  for  a  time   after 
>the  opening  of  spring    (Fig. 
64). 

373.  Cuttings  from  Dor- 
mant Stems  (stem  cuttings) 
usually  form  roots  more 
promptly  if  the  proximal 
end  is  cut  off  shortly  below 
a  node  (115).  (See  Figs.  97, 
98  and  99).  In  certain 
plants,  as  many  of  the  eoni- 
FIG.  97.  FIG.  98.  FIG.  99.  fers,  cuttings  root  more 

FIG.  97.    Stem   cutting  of  cur- 

rant.  promptly   when    cut    with    a 

FIG.  98.        Stem      cutting     of  F          *    J 

grape.    (Both   after   Bailey.)          heel,    1.    6.,   With    a    Small    por- 
FIG.       99.        Currant      cutting     .  ,,     , 

rooted.  tion  of  the  wood  oi  the  pre- 

vious year  at  the  base.     The  very  short  internodes  at 


212  Principles  of  Plant  Culture. 

the  junction  of  the  two  season's  growth  appear  to  favor 
the  emission  of  roots.  Some  varieties  of  the  grape  root 
more  readily  when  a  short  section  of  the  parent  branch 
is  removed  with  the  cutting,  forming  a  mallet-  or 
T-shaped  cutting  (mallet  cuttings}. 

The  cut  forming  the  distal  end  of  the  cutting  (115) 
is  preferably  made  somewhat  above  a  node,  in  order 
that  the  bud  may  not  loose  an  undue  amount  of  moist- 
ure by  evaporation  from  the  adjacent  cut  surface. 

Cuttings  of  certain  plants  that  do  not  readily  form 
roots  when  made  in  the  ordinary  way,  may  be  induced 
to  do  so  by  "ringing"  the  branch  from  which  the  cut- 
ting is  to  be  made  (428  d) ,  just  below  a  node  at  about 
midsummer.  Callus  will  then  form  at  the  upper  edge 
of  the  ring  (79),  and  food  will  be  stored  in  the  stem 
immediately  above  it.  In  autumn  the  branch  may  be 
severed  just  below  the  ring  and  a  cutting  made,  of 
which  the  base  shall  include  the  callused  part,  and 
which  may  be  treated  in  the  usual  manner. 

374.  The   Proper   Length    for    Stem   Cuttings    de 
pends  upon  the  conditions  under  which  they  are  to  be 
grown.     Cuttings  containing  only  one  bud  often  root 
freely   and   form   vigorous   plants   in  the    propagating 
bed,  where  heat  and  moisture  may  be  readily  controlled. 
Such  short  cuttings,  however,  are  seldom  used  except 
when  cutting   wood   is  scarce.     Cuttings    intended   for 
planting  in  the  open  ground  are  preferably  made  at 
least  six  inches  long. 

375.  How   to   Plant    Stem   Cuttings.     The    general 
rules  given  for  the  planting  of  seeds  apply  with  nearly 
equal  force  to  cuttings  of  the  stem  (344).     Single-bud 


Propagation  by  Cuttings.  213 

cuttings  should  be  planted  with  the  bud  facing  upward, 
and  one-half  to  three-fourths  inch  deep,  in  order  that 
the  developing  bud  may  readily  reach  the  surface.  Cut- 
tings of  more  than  one  bud  may  be  placed  upright  or 
at  an  angle,  at  such  a  depth  that  the  bud  at  the  distal 
end  (115)  is  about  on  a  level  with  the  surface.  In  cut- 
tings of  shrubby  plants  desired  to  produce  a  single 
stem,  the  central  buds  should  be  rubbed  off  before 
planting,  leaving  but  one  or  two  buds  at  the  distal  end 
(Fig.  97). 

376.  Propagation  from  Cuttings  of  the  Root.  Plants 
that  naturally  sucker  from  the  root  (347)  and  some 
others  may  be  propagated  from  short  pieces  of  the  root 
(root  cuttings').  For  this  purpose  roots  of  about  the 
thickness  of  a  lead-pencil  are  commonly  cut  into  pieces 
one  to  three  inches  long 
(Fig.  100),  as  soon  as  growth 
ceases  in  autumn,  and  packed 
in  boxes  with  alternate  lay- 

FIG.     100.      Root    cutting    of  J 

blackberry.      (After    Bailey.)        ers    of    moist    Sand     Or    mCSS. 

The  boxes  are  preferably  stored  in  a  cool  cellar  where 
they  may  be  examined  from  time  to  time  during  win- 
ter; the  sand  or  moss  should  be  moistened  when  it  ap- 
pears dry.  Root  cuttings  of  different  varieties  of  the 
same  plant  often  require  different  degrees  of  tempera- 
ture to  induce  the  formation  of  callus  and  buds,  hence 
the  boxes  should  be  frequently  examined,  particularly 
toward  spring,  in  order  that  those  in  which  the  cut- 
tings are  backward  in  starting  may  be  placed  in  a 
higher  temperature.  Thus  treated,  root-cuttings  of 
many  hardy  plants,  as  the  plum,  raspberry,  blackberry, 


214  Principles  of  Plant  Culture. 

juneberry,  etc.,  often  form  both  buds  and  rootlets  by 
spring,  so  that  they  may  be  planted  directly  in  the 
open  ground.  Those  of  more  tender  species,  as  the 
bouvardia,  geranium,  etc.,  will  not  start  to  the  same 
degree,  unless  placed  in  the  propagating  bed  toward 
spring  and  given  bottom  heat. 

Root  cuttings  should  be  planted  shallow,  usually  not 
more  than  one-half  to  three-fourths  inch  deep,  in  order 
that  the  developing  bud  may  soon  reach  the  light;  oth- 
erwise, as  in  too-deeply  planted  seeds,  the  reserve  food 
may  be  exhausted  before  the  shoot  reaches  the  surface. 
When  planted  in  the  open  ground  (372),  the  soil  should 
be  made  very  fine  and  carefully  pressed  about  the  cut- 
tings; if  the  weather  is  warm  and  dry,  shading  (Fig. 
64)  and  watering  will  be  necessary. 

b — Propagation  ~by  cuttings  from  active  plants  (green 
cuttings,  slips). 

377.  Nearly  AH  Plants  may  be  Propagated  from 
Green  Cuttings.  A  succulent  cutting  of  nasturtium* 
with  its  leaves  intact,  and  with  its  proximal  end  im- 
mersed in  fresh  we]l-  or  spring-water,  will  for  a  time 
absorb  sufficient  of  the  liquid  to  make  good  the  less 
from  transpiration  (74).  So  long  as  the  water  remains 
fresh  and  the  tissues  of  the  stem  are  unobstructed, 
the  water  thus  absorbed  will  answer  the  same  purpose 
to  this  cutting  as  if  it  had  been  absorbed  by  the  roots. 
Food  formation  (58)  will  continue,  and  the  growth 
current  (79)  will  transport  the  prepared  food  from  the 
leaves  into  the  stem  and  in  the  direction  of  the  roots. 
No  roots  being  present,  however,  the  growing  points  of 

*  Tropceolum. 


Propagation  by  Cuttings.  215 

roots  will  form  at  the  base  of  the  stem,  and  we  shall 
soon  have  a  rooted  cutting.  Not  all  plants,  however, 
root  freely  in  water,  pcssibly  owing  to  an  insufficient 
supply  of  oxygen  therein. 

With  very  few  exceptions,  of  which  the  greenhouse 
smilax*  is  one,  cuttings  of  the  succulent  growth  of  the 
stem,  with  a  certain  amount  of  healthy  leaf  surface  in- 
tact, will  develop  roots  in  all  plants,  under  proper  con- 
ditions of  humidity  and  temperature ;  hence  propagation 
from  green  cuttings  is  a  very  common  and  expeditious 
method  of  multiplying  plants.  The  healthy  leaf  sur- 
face, capable  of  preparing  food,  is  a  very  important 
part  of  a  green  cutting,  because  the  stem  is  less  abun- 
dantly supplied  with  reserve  food  during  the  growth 
period  than  during  the  dormant  period  (184). 

Since  the  presence  of  leaf  surface  upon  the  cutting 
greatly  promotes  transpiration  (74),  propagation  from 
green  cuttings  is  scarcely  practicable  in  the  open  air. 
Bottom  heat  (362),  with  a  comparatively  low  air  tem- 
perature, is  especially  important  with  green  cuttings,  in 
order  that  the  food  prepared  in  the  leaves  may  be  de- 
voted to  the  formation  of  roots.  A  small  leaf  surface 
on  the  cutting  is  generally  preferable  to  a  larger  one; 
in  many  plants,  a  portion  of  a  single  leaf  is  sufficient. 
The  leaf  surface  should  in  no  case  be  permitted  to  wilt, 
hence  the  cuttings  should  generally  be  sprinkled  with 
water  as  soon  as  made. 

378.  Especial  Care  is  Necessary  in  Propagating 
plants  from  Green  Cuttings.  In  planting' the  cuttings, 
the  material  of  the  propagating  bed  should  be  put  in 

*  Asparagus  meteloides. 


216  Principles  of  Plant  Culture. 

close  contact  with  the  stems,  and  no  leaves  of  the  cut- 
tings should  be  covered.  Since  roots  cannot  form  with- 
out oxygen,  the  bed  must  not  be  so  freely  watered  as 
to  exclude  all  air.  Transpiration  should  be  reduced  by 
sheltering  the  cuttings  from  the  direct  rays  of  the  sun. 
Movable  screens  used  during  sunshine  only,  are  prefer- 
able to  whitening  the  glass,  which  causes  too  much  shade 
when  the  sun  is  not  shining. 

Damping   off,   a    much-dreaded   disease   causing  cut- 
tings to  ret  at  the  surface  of  the  bed,  is  promoted  by 
excessive  heat,  over-watering,  or   insufficient 
light  or  air ;  also  by  decomposing  organic  mat- 
ter   in    the    material 
of  the  bed.    Affected 
I  cuttings     should     be 
promptly     removed 
and  the  trouble  cor- 
rected. 

379.     Green     Cut- 
tings should  be  Pot- 

^^.  ^.     Cutting      of      chrysanthe-       .«'•«,  ~ 

mum.  ted   as  Soon  as  Roots 

FIG.  102.     Rooted      cutting     of     col- 

eus.    (Both  after  Bailey.)  Form,  which  may  be 

detected  by  their  foliage  assuming  a  bright  color.  They 
should  first  be  placed  in  small  pots,  and  until  they  have 
commenced  growth  in  these,  should  be  treated  pre- 
cisely as  before  they  were  potted. 

Propagation  by  green  cuttings  includes  three  divi- 
sions, of  which  the  requirements  differ  in  some  respects, 
viz.,  propagation  by  cuttings  of  herbaceous  plants,  of 
woody  plants  and  of  the  leaf  or  parts  of  the  leaf  (leaf 
cuttings} . 


Propagation  ~by  Cuttings.  217 

380.  How  to  Make  Green  Cuttings  of  Herbaceous 
Plants.     In  herbaceous  plants  roots  develop  most  read- 
ily from  the  younger  and  more  succulent  parts  of  the 
stem.     Bend  the  shoot  near  its  terminus  in  the  form 
of  a  U,  and  then  press  the  parts  together.     If  the  stem 
breaks   with  a  snap,   it  is  in  the  proper   condition  to 
root  promptly;  if  it  bends  without  breaking  it  has  be- 
come too  hard.     Cutting  below  a  node  (115)   is  not  es- 
sential to  the  formation  of  roots  in  herbaceous  plants.* 

While  the  propagating  house  or  hotbed  is  necessary 
to  the  extensive  multiplication  of  herbaceous  plants  by 
green  cuttings,  the  amateur  may  readily  propagate  a 
limited  number  of  plants  by  the  so-called  "saucer  sys- 
tem." The  cuttings  may  be  placed  in  glazed  saucers 
containing  sand  that  should  be  kept  saturated  with 
water.  The  saucers  may  be  set  in  any  warm,  well- 
lighted  place,  as  the  window  of  a  living  room.  The 
stems  being  in  this  case  in  contact  with  the  water  in 
the  bottom  of  the  saucer,  the  cuttings  require  less  shad- 
ing than  those  in  the  propagating  bed. 

381.  How    to    Make    Green    Cuttings    of    Woody 
Plants.     Cuttings    of    woody    plants     are    preferably 
made  of  harder  growths  than  those  best  suited  to  herba- 
ceous   plants.     They    should    be    selected    from   young 
shoots  of  medium  size  and  from  half-mature  wood,  and 
should    generally  contain    from    two  to  three    nodes, 
though  where  the  material  for  cuttings  is  scarce,  single 
buds  may  be  used  in  many  plants.     The  base  of  the 

*  In    a    few   plants,   as   the   dahlia,    the   presence   of   a  dormant 
bud  at  the  crown  is  essential   to   the  development  of  the  stem  the 
succeeding    year.     Cuttings     of    such    plants    should    therefore    be 
made  below  a  node,  if  the  roots   are   desired  for  future  use. 
15 


218 


Principles  of  Plant  Culture. 


cutting  is  preferably  cut  shortly  below  a  node,  but  this 
is  not  essential  in  all  plants. 

In  this  kind  of  propagation  a  mild  bottom  heat  is 
helpful;  though  it  is  sometimes  carried  on  during  the 
summer  months  without  artificial  heat. 

382.  Propagation  by  Leaf  Cuttings.  A  considerable 
number  of  plants,  including  the  bryophyllum,  begonia, 
gesnera  and  others,  readily  develop  growing  points  of 
the  stem  and  roots  upon  their  leaves,  a  fact  often 
turned  to  account  in  propagating  these  plants.  Well- 


PIG.  103.  Leaf  of  begonia  on  surface  of  propagating  bed,  form- 
ing young  plants.  (After  Bailey.) 

matured  leaves,  with  the  principal  nerves  cut  across  on 
the  under  side,  are  held  in  close  contact  with  the  sur- 
face of  the  propagating  bed  by  pegging  or  by  light 
weights,  or  the  leaf  may  be  cut  into  pieces,  which  may 
be  placed  in  the  propagating  bed  and  treated  as  ordi- 
nary green  cuttings  (378). 

The  leaves  of  the  bryophyllum  form  rootlets  and 
buds  from  the  notches  on  their  borders  wherever  these 
chance  to  come  in  contact  with  a  moist  medium. 


Propagation  Toy  Grafting.  219 

b— Propagation   by  grafting. 

383.  Grafting  consists  in  placing  together  two  por- 
tions of  a  plant  or  of  different  plants,  containing  living 
cambium  (68)  in  such  a  way  that  their  cambium  parts 
are  maintained  in  intimate  contact.  If  the  operation 
is  successful,  growth  will  unite  the  two  parts  (69), 
and  plant  processes  will  go  on  much  as  if  the  parts 
had  never  been  separated.  The  union  usually  takes 
place  most  rapidly  when  the  cambium  cells  are  in  the 
state  of  most  rapid  division,  i.  e.,  when  growth  is  most 
vigorous. 

The  more  intimate  the  contact  of  the  cambium  in  the 
parts  brought  together,  and  the  less  injury  their  cells 
sustain  in  adjusting  them,  the  more  likely  are  they  to 
unite. 

The  plant  that  it  is  desired  to  change  by  grafting  is 
called  the  stock,  and  the  part  designed  to  be  united  to 
the  stock  is  called  the  don  (scion),  graft  or  ~bud. 

Although  the  tissues  of  two  plants  of  differing  char- 
acter often  unite  in  grafting,  each  of  the  united  parts 
almost  always  retains  its  individual  character.  For  ex- 
ample, if  one  or  more  buds  of  the  Ben  Davis  apple  are 
caused  to  unite  by  grafting  with  the  stem  of  a  Baldwin 
apple  the  parts  that  grow  thereafter  from  the  Ben 
Davis  buds,  though  nourished  by  sap  that  has  passed 
through  the  Baldwin  roots  and  stem,  with  rare  excep- 
tions, continue  to  be  Ben  Davis,  while  the  parts  that 
grow  from  the  Baldwin  stock  continue  to  be  Baldwin. 
To  this  fact  is  due  the  chief  value  of  grafting,  viz.,  it 
enables  us  to  change  the  character  of  a  plant. 


220  Principles  of  Plant  Culture. 

384.  Objects   of  Grafting.     Grafting   enables  us 

a — To  change  a  plant  of  an  undesirable  variety  into 
one  or  more  desirable  ones; 

b— To  preserve  and  multiply  plants  of  varieties  that 
cannot  be  preserved  or  multiplied  by  growing  them 
from  their  seeds ; 

c — To  hasten  the  flowering  or  fruiting  of  seedlings 
grown  with  a  view  to  improving  varieties ; 

d— To  change  the  size  of  trees,  as  to  make  them  more 
dwarf ; 

e— To  restore  lost  or  defective  branches; 

f — To  adapt  varieties  to  special  soils; 

g— To  save  girdled  trees; 

h— To  avoid  insect  injury  to  the  trunk  or  root,  as  in 
grafting  the  peach  on  the  plum,  or  the  European  grape 
on  the  American. 

385.  The  Plants  that  Unite  by  Grafting.     Plants  of 
different  varieties  of  the  same  species   (21)   almost  al- 
ways unite  by  grafting.     Examples,  the  Ben  Davis  and 
Baldwin  apples,  the  Bartlett  and  Seckel  pears. 

Plants  of  different  species  of  the  same  genus  (21) 
often  unite  by  grafting.  Examples,  the  peach  unites 
with  the  plum,  many  pears  unite  with  the  quince;  the 
tomato  unites  with  the  potato. 

Plants  of  different  genera  in  the  same  family  or  or- 
der (21) ,  sometimes  unite  by  grafting.  Examples,  the 
chestnut  unites  with  the  oak;  the  pear  unites  with  the 
thorn. 

Plants  belonging  to  different  families  rarely  unite 
by  grafting.  The  oak  and  walnut  and  the  fir  and  lin- 
den have  been  grafted. 


Propagation  ~by  Grafting.  221 

The  apparent  resemblance  of  two  plants  of  different 
species  is  not  always  evidence  that  they  will  unite  by 
grafting,  e.  g.,  the  peach  and  apricot,  though  resem- 
bling each  other  in  many  respects,  do  not  readily  unite 
by  grafting,  but  both  unite  freely  when  worked  upon 
the  plum,  though  the  latter  apparently  differs  from 
both  the  peach  and  apricot  more  than  these  differ  from 
each  other. 

Many  plants  unite  freely  when  grafted  in  one  direc- 
tion, that  fail  to  unite  when  worked  in  the  opposite 
direction;  e.  g.,  many  cultivated  cherries  unite  freely 
when  worked  upon  the  mahaleb  cherry,  while  the  latter 
fails  to  unite  when  worked  upon  any  of  the  cultivated 
cherries;  many  pears  unite  freely  when  grafted  upon 
the  quince,  but  the  quince  does  not  freely  unite  when 
worked  upon  the  pear.  The  only  sure  way  of  deter- 
mining what  species  may  be  united  by  grafting  is  by 
trial. 

Three  principal  kinds  of  grafting  are  in  use,  viz., 
cion  grafting,  budding  and  approach  grafting. 

386.  Cion  Grafting  is  used  in  grafting  on  roots 
(root-grafting)  and  very  often  in  grafting  on  the  stem, 
especially  on  large  trees.  The  cion  is  a  portion  of  the 
dormant  stem,  of  the  variety  it  is  desired  to  propagate. 
It  should  generally  be  of  the  preceding  season's  growth 
and  should  always  contain  one  or  more  healthy  leaf- 
buds*  (131).  It  is  probably  best  to  cut  cions  from 
trees  known  to  be  fruitful.  Cions  are  usually  cut  in 
autumn  or  during  mild  weather  in  winter  or  early 

*  Flower-buds  are  occasionally  used,  but  should  be  avoided  ex- 
cept in  special  cases. 


222  Principles  of  Plant  Culture. 

spring,  and  are  commonly  stored,  until  needed  for  use, 
in  a  cool  cellar  packed  in  moist  sawdust,  moss  or 
leaves.  In  climates  of  severe  winters,  they  should  al- 
ways be  cut  in  autumn.  Cions  should  not  be  kept  so 
moist  as  to  cause  swelling  of  the  buds  or  the  forma- 
tion of  callus  (72),  nor  so  dry  as  to  cause  shriveling. 

In  cion  grafting  the  proximal  end  of  the  cion  (115) 
is  joined  to  the  distal  end  of  the  stock  if  the  stock  is  a 
stem,  or  to  the  proximal  end  if  it  is  a  root  in  such  a 
way  that  the  cambium  layers  of  the  two  coincide  in  at 
least  one  place.  Cion  grafting  in  the  open  air  is  usu- 
ally most  successful  when  performed  just  before  or 
during  the  resumption  of  active  growth  in  spring,  and 
the  cion  is  thought  to  unite  more  readily  if  in  a  slightly 
more  dormant  condition  than  the  stock,  possibly  owing 
to  its  more  ready  absorption  of  water  when  in  this 
state. 

The  joints  made  in  cion  grafting  are  generally  coated 
with  a  thin  layer  of  grafting-wax  (387)  or  bound  in 
grafting  paper-,  cloth-  or  cord  (308,  309),  to  prevent 
evaporation  and  to  keep  out  water.  Sometimes  the 
whole  exposed  part  of  the  cion  is  waxed. 

387.  To  Make  Grafting- Wax  for  cleft-grafting 
(392),  melt  together  four  parts,  by  weight,  of  un- 
bleached rosin,  two  parts  of  beeswax  and  one  part  of 
beef  tallow;  pour  into  water,  and  when  sufficiently 
cool,  work  with  the  hands*  until  the  mass  assumes  a 
buff  color;  make  into  rolls  and  wrap  with  parafined 
(waxed)  paper  to  prevent  the  rolls  from  sticking  to- 
gether. Several  other  formulas  are  in  use. 

*  The  hands  should  be  greased  before  touching  the  wax  to  pre- 
vent sticking. 


Propagation  by  Grafting. 


223 


For  whip-grafting  (390),  where  waxed  cord,  cloth  or 
paper  is  used,  the  beeswax  may  be  omitted  from  the 
above  formula,  or  one-half  more  tallow  may  be  added. 


FIG.  104.  FIG.  105.      FIG.  106.      FIG.  107.      FIG.  108.  FIG.  109.  FIG.  110. 

FIG.  104.  Grafting  knife.  This  should  be  of  excellent  steel. 
The  curve  in  the  blade  is  not  essential. 

FIG.  105.  Cion  used  for  whip-,  root-  or  cleft-grafting,  one- 
fourth  natural  size. 

FIG.  106.  Seedling  root,  used  in  root-grafting,  one-fourth  nat- 
ural size. 

FIG.  107.  Cion  shaped  ready  for  insertion,  reduced  nearly  one'- 
half. 

FIG.  108. 

FIG.  109. 

FIG.  110. 


Portion  of  seedling  root,   shaped  to  receive   the  cion. 

The  cion  and   portion   of  root,   put  together. 

The  same  as  Fig.   109,    wrapped  with  grafting  paper. 


224  Principles  of  Plant  Culture. 

388.  Grafting  Cord  is  made  by  soaking  balls  of  com- 
mon wrapping  twine  in  melted  grafting-wax. 

389.  Grafting  Paper  is  made  by  painting  thin  ma- 
nil]  a  paper  with  melted  grafting-wax.     For  painting, 
the  paper  is  preferably  spread  out  on  a  board  of  the 
exact  size  of  the  sheet;  to  prevent  too  rapid  cooling  of 
the  wax  the  board  should  be  heated.     The  wax  should 
be  heated  hot  enough  to  spread  easily,  but  not  so  hot 
that    it   is    absorbed   by   the   paper.     Thin    muslin    or 
calico  is  often  used  instead  of  paper. 

Grafting  paper  and  grafting  cloth  should  be  stored 
in  a  cool,  moist  place  to  preserve  their  adhesiveness. 

Many  kinds  of  cion  grafting  slightly  differing  in  de- 
tails have  been  described,  but  the  more  important  are 
whip-grafting,  cleft-grafting  and  side-grafting. 

390.  In     Whip-Grafting      (splice-grafting,     tongue, 
grafting)   the  cion  and  stock,  are  both  cut  off  with  a 
sloping  cut,  about  an  inch  long,  after  which  a  tongue 
is  formed  on  each  by  splitting  the  wood  longitudinally 
a  short  distance  (Figs.  107,  108) .     The  cion  is  best  cut 
behind  a  bud,  as  shown. 

In  joining,  the  tongue  of  the  cion  is  inserted  into  the 
split  of  the  stock,  so  that  the  cambium  line  of  the  cion 
and  stock  (68)  coincide  on  one  edge,  and  the  two  are 
crowded  together  with  considerable  force,  after  which 
the  joint  is  wrapped  with  a  narrow  strip  of  grafting 
paper  or  grafting  cloth  (389),  or  wound  with  grafting 
cord  (388).  Sometimes  the  joints  are  simply  tied  with 
rmwaxed  cord. 

Whip-grafting  is  generally  used  when  the  stock  is 
little  if  any  thicker  than  the  cion.  It  is  much  used  by 


Propagation  by  Grafting.  225 

nurserymen  in  certain  localities  in  grafting  the  apple 
and  some  other  fruits  upon  roots  (root-grafting  (391)). 

Whip-grafting  is  also  considerably  used  in  some  cli- 
mates of  severe  winters,  in  top-grafting  or  "top-work- 
ing" apple  trees  in  the  nursery,  in  order  to  give  cer- 
tain slightly-tender  varieties  the  benefit  of  a  specially 
hardy  stock.  This  grafting  is  performed  on  two  or 
three-year-old  trees,  that  have  been  grown  from  root 
grafts.  The  trunk  is  cut  off  at  the  height  it  is  desired 
to  form  the  head  of  the  tree,  and  a  cion  of  the  variety 
to  be  propagated  is  inserted;  or  several  cions  are  in- 
serted in  as  many  branches.  The  latter  method,  while 
more  expensive,  has  the  advantage  of  giving  to  the 
top-grafted  trees  the  branch  formation  of  the  stock, 
which  is  sometimes  important. 

As  growth  starts  on  the  top-grafted  trees,  shoots  that- 
push  out  from  the  stock  should  be  rubbed  off  to  pre- 
vent them  from  robbing  the  cions  of  nourishment. 

391.  Root  Grafting  is  generally  performed  in  winter 
and  in-doors.  The  stocks  are  small  trees,  grown  one  or 
two  years  from  seed  (seedlings).  These  are  dug  in  au- 
tumn, and  stored  as  recommended  for  cions  (386). 
When  ready  for  grafting,  the  roots  are  washed  and 
trimmed  by  cutting  off  the  larger  branch  roots,  after 
which  the  stem  is  cut  off  at  the  crown,  and  the  end  of 
the  root  (115)  is  shaped  as  directed  above  (390).  It 
is  then  cut  off  two  or  three  inches  down,  and  the  re- 
maining root,  if  sufficiently  thick,  is  shaped  for  another 
stock.  Three  or  four  stocks  are  sometimes  made  from 
a  single  root.  As  a  rule,  the  stocks  should  not  be  less 
than  three-sixteenths  inch  in  diameter,  nor  less  than 
two  inches  long. 


226  Principles  of  Plant  Culture. 

Some  nurserymen  prefer  to  make  but  a  single  stock 
from  one  root  ("whole-root"  grafts). 

Different  nurserymen  cut  the  cions  for  root-grafts 
from  two  to  six  inches  long.  In  climates  subject  to 
drought  in  summer  and  severe  freezing  in  winter,  the 


FIG.  111.  Shaping  the  cions  for  root-grafting.  A,  making  the 
"long  cut";  B,  cutting  the  "tongue";  C,  cutting  off  the  cion. 
These  positions,  and  the  movements  they  indicate,  are  adapted  to 
rapid  work. 

longer  cions  are  more  satisfactory,  as  they  permit  the 
stock  to  be  covered  to  a  greater  depth,  and  encourage 
rooting  from  the  cion,  which  is  sometimes  regarded  as 
an  advantage. 

Root-grafts  should  be  stored  until  time  for  planting 
out,  as  directed  for  cions  (386). 

392.  Cleft-Grafting  is  generally  employed  when  the 
stock  is  considerably  thicker  than  the  cion.  The  cut-off 
end  of  the  stock  is  split  across  its  center,  with  a  graft- 
ing chisel  (Pig.  112),  and  the  proximal  end  of  the  cion 
(115),  which  is  cut  wedge-shaped  and  a  little  thicker  on 
one  edge  than  the  other,  is  so  inserted  into  the  cleft 
that  the  cambium  of  the  thicker  edge  of  the  cion  forms 
a  line  with  the  cambium  of  the  stock  (Figs,  113,  114. 
115).  Success  is  promoted  if  the  wedge-shaped  por- 
tion of  the  cion  contains  a  bud  on  its  thicker  edge. 
When  the  stock  exceeds  an  inch  in  thickness,  two  cions 


Propagation  by  Grafting. 


227 


are  usually  inserted  (Fig.  114),  to  increase  the  chances 
of  success.  The  elasticity  of  the  stock  should  exert 
sufficient  pressure  to  maintain  very  close  contact  be- 


tween it  and  the 
tightly  bound 
The  cions  should 
yond  the  end  of 
cut  is  usually 


cion;  otherwise  it  should  be 
with  cord  or  raffia  (393). 
contain  at  least  one  bud  be- 
the  stock.  The  wedge-shaped 
made  about  one  inch  long, 
and  the  cion  should  be  in- 
serted into  the  cleft  as  far 
as  the  length  of  the 
wedge,  after  which  all 
the  exposed  wounded 
J/j3  I  if  surfaces,  including 


FIG.  112.  Grafting 
chisel  for  making 
the  cleft  in  cleft- 
grafting.  The  point 
at  the  right  is  for 
holding  the  cleft 
open  during  inser- 
tion of  cions.  The 
projection  above  is 
for  driving  this 
point  in  or  out;  one- 
fifth  natural  size. 


PIG.  113.     FIG.  114.  FIG.    115. 

FIG.  113.  Cion  shaped  ready  for  insertion 
in  cleft.  (After  Bailey.) 

FIG.  114.  Cions  inserted  in  cleft,  ready 
for  waxing. 

FIG.  115.  Cross-section  of  Fig.  113  (Af- 
ter Maynard).  C,  cambium  layer  of  stock; 
C',  cambium  layer  of  cion.  The  cambium 
layers  of  the  outer  edge  of  the  cion  should 
form  a  continuous  line  with  that  of  the 
stock.  The  cion  is  made  a  little  thinner 
at  its  inner  edge  to  permit  the  pressure  of 
the  stock  to  be  exerted  at  the  outer  edge. 


the  distal  end  of  the  cion,  should  be  coated  with  graft- 
ing-wax (387). 

Cleft-grafting  is  most  used  in  top-grafting  old  trees. 
Four  to  six   of  the  main  branches,  located  as  nearly 


228 


Principles  of  Plant  Culture. 


gtSS?  SSSf  '  * 


equidistant   as    possible    (Fig.    116),   are    selected    for 

grafting,  and  it  is  desirable  to  graft  these  rather  near 

to  the  top  of  the  trunk. 

Branches  exceeding  two  inches 

in  diameter  should  not,  as  a  rule, 

be    grafted.     About   half  of   the 

top    of   the   tree   should   be    cut 

away   just   before    the   grafting, 

leaving  some  branches  to  utilize 

a  part  of  the  sap.     The  more  or 

less    horizontal    branches    should 

generally  be  selected    for   graft- 

ing,  and  in  these,  the  cleft  should 

be  made  horizontally,  to  give  the 

two   cions  inserted  an  equal  op- 

portunity  for  growth.     If  both  the  cions  in  a  branch 

grow,  the  weaker  one  should  be  pruned  off  later.  As 
growth  starts,  shoots  from  the 
stock  must  be  rubbed  off 
(390). 

The    spring     following    the 
top-grafting,  all  or  a  part  of 
the  branches  left  on  the  stock 
at  grafting  should  be  pruned 
FIG.   117.     cieft-graft    in  off  to  encourage  growth  of  the 

trunk  of  old  grape  vine.  The 

cions     are     usually     inserted   grafts.       If    the    tree     IS    large 

below     the     surface     of     the 

ground  in  grafting  the  grape,    and    of    a    vigorous    Variety,    it 

and  no  wax  is  used.     (After 

is  wise  to  leave  a  part  of  thes^ 
branches  until  the  second  spring. 

393.  Side-Grafting   if   chiefly  practiced   with  plants 
in  leaf,  under  glass.     The  cion  is  joined  at  the  side  of 


Propagation  by  Grafting.  22'j 

the  stock,  which  is  usually  not  cut  off,  and  is  secured 
in  place  by  wrapping  tightly  with  grafting  cloth  or 
raffia.  Three  slightly  different  methods  are  in  use. 

a— A  shaving  of  bark,  thick  enough  to  reach  into  the 
cambium  layer,  is  removed  from  the  side  of  the  stock 
by  making  a  long  vertical  cut  and  a  short  transverse 
cut  at  the  base,  and  to  this  cut  surface  the  cion  is  care- 
fully fitted,  and  bound  with  raffia.  This  method  is  called 
veneer-grafting. 

b— A  sloping  cut  is  made  rather  deeply  into  the  sap- 
wood  of  the  stock,  into  which  the  cion,  after  being  ta- 
pered at  its  base  to  the  form  of  a  wedge, 
is  inserted  (Fig.  118),  and  the  parts  are 
then  held  closely  together  by  binding  with 
raffia.  This  method  is  generally  employed 
in  herbaceous  grafting,  as  with  the  po- 
tato, tomato,  etc.  It  is  also  much  used  in 
grafting  evergreens  under  glass,  and  oc- 
casionally in  grafting  outdoor  nursery 
trees.  In  the  latter  case,  a  coating  of 
g5ft  "inserted  Sr^'mS  wax  is  usually  substituted  for 

ready  for  tying-.'  the   tying. 

c — A  short,  transverse  incision  is  made,  and  imme- 
diately below  this,  a  somewhat  longer,  vertical  cut— 
the  two  cuts,  which  are  just  deep  enough  to  reach 
through  the  bark,  forming  a  T  (Fig.  121).  The  cion 
is  then  cut  off  with  a  long,  sloping  cut,  and  the  point 
inserted,  the  cut  surface  inward,  beneath  the  two  lips 
of  bark  formed  by  the  T-cut,  after  which  the  cion  is 
crowded  downward  until  its  cut  surface  is  in  contact 
with  the  cambium  layer  of  the  stock,  when  the  juncture 
is  bound  with  raffia. 


230  Principles  of  Plant  Culture. 

394.  Budding  is  now  extensively  employed  in  propa- 
gating fruit  trees,  roses  and  the  varieties  of  deciduous 
ornamental   trees    and   shrubs.     A    (usually    dormant) 
leaf-bud,  with  a  small  portion  of  surrounding 
bark  (Fig.  120),  is  placed  in  contact  with  the 
cambium  layer  of  the  stock.     Budding  may  be 
successful  whenever  the  cells  of  the  cambium 
layer   are  in   a  state   of  active 
division,    as    indicated    by    the 
ready   separation  of   the 
bark  from  the  wood.  In 
climates     having     severe 
winters,   budding   is  most 
satisfactory     when     per- 
formed near  the   end  of 
the    growing    sea- 
son and  with  fully 
matured   buds,    in 
order      that      the 
buds  may  not  ex- 
expand     until    the 
following    spring ; 

FIG.  119.  FIG.  121.  FIG.  122.  FIG.  120.   tllUS       the       shoots 

FIG.  119.     Shoot      containing      buds.       The  .  ,,  , 

white   spaces    about    the    buds    indicate    the  gl'OWing    irom    the 
amount  of  bark   to  be  cut  off  with  the  bud.    .  .„ 

The  shoot  is  inverted  for  cutting  the  buds,    inserted     DUd     Will 
FIG.  120.     Bud    cut    off ,  ready  for  insertion.  ,  .,  wl,nlp 

FIG.  121.     Bud   partially   inserted    between  u< 

the  lips  of  the  stock.  season   for  growth 


FIG.  122.     Bud     inserted     and     tied, 
after   Bailey.) 


(All 


and  maturity. 
With  plants  that  unite  freely  and  with  the  stock  in 
the  proper  condition, 


Propagation  by  Grafting.  331 

395.  Success  in  Budding   Depends  Upon 

a — A  fresh  condition  of  the  buds;  these  must  not  be 
in  the  least  shriveled  from  dryness. 

b — The  proper  removal  and  insertion  of  the  bud; 
the  growing  point  of  the  latter  (66)  must  not  be  in- 
jured. If  this  comes  out,  leaving  the  bud-scales  par- 
tially hollow,  the  bud  will  not  grow,  even  if  properly 
inserted.  The  bud  should  be  inserted  'promptly  to 
avoid  loss  of  moisture. 

G—The  proper  wrapping  of  the  wounded  bark,  to 
prevent  evaporation  and  exclude  moisture.  The  liga- 
ture should  not  cover  the  bud. 

d — The  removal  of  the  ligature  after  the  union,  to 
permit  expansion  of  the  stock. 

e — The  cutting  off  of  the  stock  just  beyond  the  bud, 
when  the  latter  commences  growth,  to  stimulate  its  de- 
velopment. 

Two  methods  of  budding  are  in  use,  viz.,  T-  or  shield- 
budding  and  ring-  or  annular-budding. 

396.  In  T-Budding,  which  is  the  more  common  and 
expeditious  method,  a  short  shaving,  containing  a  hard 
and  plump  bud,  cut  deep  enough  to  reach  through  the 
cambium    (Fig.   120),  is  inserted  beneath  the  bark  of 
the  stock,  as  described  for  side-grafting   (393c). 

The  buds,  wrhich  should  be  plump  and  mature,  and 
of  the  variety  it  is  desired  to  propagate,  are  taken  from 
shoots  of  the  current  season's  growth.  These  shoots 
("bud  sticks")  (Fig.  119)  shoulcLbe  cut  the  day  the 
buds  are  to  be  inserted,  and  should  be  trimmed  at  once, 
and  rolled  in  damp  cloth,  to  prevent  loss  of  moisture. 
The  trimming  consists  in  cutting  off  the  leaves,  saving  a 


232  Principles  of  Plant  Culture. 

bit  of  the  leaf  stem  to  serve  as  a  handle  while  inserting 
the  buds.  The  stocks,  whether  grown  from  seeds  or 
from  cuttings,  are  usually  of  one  or  two  season 's  growth. 
The  lower  branches  of  the  stock  are  cut  off  up  to  three 
inches  or  more  from  the  ground,  and  a  smooth  place  is 
selected  for  the  bud,  usually  on  the  side  least  exposed 
to  the  sun's  rays.  With  the  budding  knife,  a  T-shaped 
cut  is  made  on  the  stock  (393  c)  about  two  inches  above 


FIG.  123.  A  lesson  in  budding.  The  left-hand  student  is  cut- 
ting a  bud;  the  central  one  is  lifting  the  lips  of  the  bark  with  the 
spatula  of  his  budding  knife;  the  right-hand  student  is  tying 
the  bud. 

the  ground.  A  bud  is  then  cut  from  the  bud  stick,  by 
inserting  the  blade  of  the  budding-knife  about  a  fourth 
of  an  inch  below  the  bud,  at  such  an  angle  that  the 
back  of  the  blade  nearly  touches  the  bark  of  the  stick. 
The  blade  is  passed  just  behind  the  bud,  touching  the 
wood,  but  not  removing  much  of  it,  and  then  turned  a 
little,  running  out  about  a  fourth  of  an  inch  above  the 
bud  (Fig.  120).  Often  the  knife  does  not  run  out,  but 
the  bark  is  cut  off  square,  a  quarter  of  an  inch  abovf 
the  bud,  as  indicated  in  Fig.  119. 


Propagation  by  Grafting. 


233 


With  the  spatula  of  the  budding  knife  (397),  the  lips 
of  bark  in  the  angles  of  the  T-cut  are  loosened  from  the 
wood,  when  the  bit  of  bark  bearing  the  bud  is  slipped 
down  behind  them  (Fig.  121),  with  the  bud  pointing 
upward,  until  the  top  end  of  the  bit  of  bark  is  just 
below  the  horizontal  cut  of  the  T.  Some  budders  do 
not  use  the  spatula,  but  raise  the  lips  of  bark  with  the 
blade  of  the  budding  knife.  The  center  of  a  strip  of 
moistened  raffia  is  then  applied  to  the  stock  just  below 
the  inserted  bud;  the  ends  of  the  strip  are  crossed  on 
the  opposite  side  of  the  stock,  brought  forward  and 
again  crossed  just  above  the  bud, 
thus  covering  the  horizontal  cut  of 
the  T.  The  ends  of  the  raffia  are 
then  brought  behind  the  stock,  tied 


FIG.  124.  FIG.  125.    FIG.  126. 

FIG.  124.     Man   budding   in     nursery    row.      (After   Bailey.) 
FIG.  125.     Budding   knife   with   ivory  spatula    on   the   end   oppo- 
site  the    blade. 

FIG.  126.     Budding  knife   made   from    erasing  knife  by  rounding 
the   edge  at  A. 

in  a  half  knot,  and  drawn  moderately  tight  (Fig.  122), 
pressing  the  lips  down  snugly  about  the  bud,  which 
now  protrudes  between  the  lips. 

If  the  bud  "takes,"  it  will  unite  with  the  stock  in  a 
few  days.     The  raffia  should  be  taken  off  in  about  ten 


234  Principles  of  Plant  Culture. 

days,  by  cutting  it  on  the  back  side  of  the  stock,  to 
enable  the  latter  to  expand  by  growth. 

397.  The  Budding  Knife  should  contain  a  blade  of 
good   steel,   shaped   as    indicated   in   Fig.    125,   and   a 
round-edged  spatula  for  lifting  the  bark.     The  spatula 
is  Jbetter  placed  on  the  back  of  the  blade,  as  shown  in 
Fig.    126. 

398.  Ring    Budding  is   used  to  some   extent  in  the 
propagation  of  thick-barked  plants,  as  the  hickory  and 
magnolia.     A  section  of  bark  is  removed  nearly  or  en- 
tirely around  the  stock,  and  a  similar  section  contain- 
ing a  bud  from  the  variety  it  is  desired  to  propagate, 
is  fitted  to  its  place  and  snugly  bound  with  raffia.  Ring 
budding  is  oftener  performed  in  spring  than  later  in 
the  season. 

399.  Approach    Grafting   is    now   seldom    employed, 
except  in  a  few  plants  that  unite  poorly  by  other  meth- 
ods.    It  is  only  possible  between  two   plants  in  close 
proximity,  or  between  parts  of  the  same  plant,  since 
the  graft  is  not  severed  from  the  parent  until  it  has 
united  with  the  stock.     The  plants  are  nourished  by 
their  own  roots  until  the  union  takes  place. 

Approach  grafting  is  performed  during  or  just  pre- 
vious to  the  growing  season.     The   parts  are  held  in 
contact   by   binding    them   with    raffia;    the     juncture 
should  also  be  waxed  if  the  work  is  done  in  the  open  air. 
Two  methods  of  approach  grafting  are  in  use: 
a — A  shaving  reaching  into  the  cambium  layer  is  re- 
moved from  both  stock  and  graft  on  the  sides  toward 
each  other  (Fig.  127),  and  the  cut  surfaces  are  brought 
together  and  closely  bound  until  they  unite  (Fig.  128), 


Transplanting. 


235 


after  which  the  graft  is  cut  off  below,  and  the  stock 
above,  the  union. 

b — The  top  of  the  stock  is  cut  off  with  a  long  sloping 
cut,  preferably  behind  the  bud,  and  the  cut  surface  of 
the   remaining   part    is   inserted   be- 
neath the  bark  of  the  graft,  as  de- 
scribed in   side-grafting   (393c),  ex- 
cept that  the  T-cut  is  inverted,  and 
the  stock  is  inserted  from  beneath. 


FIG.  127. 


PIG.  128. 


FIG.  127.  Two  plants  prepared  for  approach  grafting.  The  cut 
surfaces,  a  a,  are  to  be  placed  together  and  bound. 

FIG.  128.  Two  plants  bound  together  for  approach  grafting. 
(After  Bailey.) 

The  graft  is  cut  off  below  the  point  of  union  when 
the  parts  are  fully  united. 

In  both  these  methods  the  graft  should  be  severed 
gradually  to  avoid  a  check  to  the  growth. 

SECTION  II.     TRANSPLANTING. 

400.  Transplanting  consists  in  lifting  a  plant  from 
the  medium  in  which  its  roots  are  established,  and  in 


236  Principles  of  Plant  Culture. 

replanting  the  latter  in  a  different  location.  Trans- 
planting is  a  violent  operation  because  the  younger 
roots  with  their  root-hairs  that  absorb  the  greater  part 
of  the  water  required  by  the  plant  (101)  are,  as  a  rule, 
largely  sacrificed  in  the  lifting  process.  The  water 
supply,  so  vitally  important  to  the  plant  (62),  is  thus 
greatly  curtailed  until  new  root-hairs  can  be  formed. 

Vigorous  plants  are  generally  better  able  to  endure 
transplanting  than  feebler  ones,  because  they  can  sooner 
repair  the  damage  done  to  their  roots.  It  follows  that 
plants  endure  transplanting  with  less  facility  as  they 
advance  in  age  beyond  the  period  of  greatest  vigor  (9). 

401.  The  Most  Favorable  Time  for  Transplanting, 
in  the  case  of  plants  that  live  more  than  one  year,  is 
during  the  dormant  period,  because  growth  processes 
are  then  least  active,  and  comparatively  little  water  is 
needed.  In  countries  having  mild  winters,  the  most 
favorable  time  for  transplanting  is  generally  at  the  be- 
ginning of  the  dormant  period,  provided  this  comes  at 
a  moist  season  of  the  year.  The  roots  will  then  have 
time  to  slowly  callus  over  their  wounds  and  to  form 
new  rootlets,  and  thus  be  prepared  for  active  growth  in 
spring.  But  in  countries  of  severe  winters,  where  the 
roots  are  largely  frozen  in  the  soil  for  two  or  three 
months,  and  in  countries  in  which  the  autumn  is  gener- 
ally dry,  spring  is,  as  a  rule,  the  more  favorable  season 
for  transplanting. 

Trees  that  have  been  long  exposed  to  cold,  drying 
winds  and  have  thus  suffered  depletion  of  water  from 
their  buds  and  branches,  are  better  not  lifted  until  the 
buds  begin  to  swell.  This  is  especially  true  of  ever- 


Transplanting.  237 

green  trees  in  severe  climates.  Being  always  in 'leaf 
these  require  more  careful  treatment  than  deciduous 
trees. 

We  shall  consider  transplanting  under  three  divi- 
sions, viz.,  a,  lifting  the  plant;  b,  removing  the  plant; 
and  c,  replanting  the  plant. 

A— LIFTING    THE    PLANT. 

402.  The  object  to  be  obtained  in  this  operation 
should  be  to  remove  the  roots  from  the  soil  with  the 
least  possible  damage  consistent  with  reasonable  econ- 
omy of  time  and  labor.  Plants  in  low  vigor  'should 
receive  especial  care  in  this  respect.  Very  young 
plants,  as  of  tobacco,  cabbage,  lettuce,  etc.,  grown 
thickly  in  the  seed-bed,  are  often  pulled  from  the  soil 
with  the  hands.  In  this  case,  the  soil  of  the  bed  should 
first  be  saturated  with  water,  in  order  that  the  roots 
may  be  broken  as  little  as  possible,  and  may  come  up 
with  more  or  less  adhering  soil.  It  is  generally  prefer- 
able to  grow  such  plants  in  drills  rather  than  broad- 
cast. This  enables  them  to  be  drawn  from  the  soil  with 
less  damage  to  their  roots. 

Trees  and  shrubs  sufficiently  grown  for  their  final 
planting  out  should  be  more  carefully  handled.  If  it  is 
necessary  to  cut  off  the  main  roots,  the  farther  from 
the  trunk  this  is  done,  the  better  for  the  tree,  and  the 
spade  used  should  be  kept  as  sharp  as  possible.  The 
roots  should  not  be  barked,  mangled  or  split  by  the 
digging  tools,  as  is  so  often  done  with  nursery  stock. 
Tree-digging  machines  are  now  much  used  by  the 
larger  nurserymen. 


238  Principles  of  Plant  Culture. 

403.  Lifting  Large  Trees.  Trees  considerably  larger 
than  nursery  sizes  are  best  lifted  when  the  ground  is 
frozen  about  their  roots.  A  trench  may  be  dug  about 
the  tree  before  the  ground  freezes,  deep  enough  to  per- 
mit the  severing  of  the  main  roots,  and  a  hole  for  the 
reception  of  the  cylinder  of  earth  left  within  the  trench 
should  also  be  dug  at  the  place  to  which  it  is  desired  to 
remove  the  tree.  This  cylinder  should  be  large  enough 
so  that  the  tree  is  left  with  abundant  roots,  or  as  large 
as  can  be  removed  with  the  apparatus  at  hand.  When 
the  ground  is  frozen  to  the  proper  depth,  the  tree  may 
be  tipped  over  by  means  of  a  rope  and  windlass,  after 
which  the  cylinder  of  earth  inclosing  the  roots  may  be 
pried  up  sufficiently  to  allow  some  low  vehicle  to  be 
placed  beneath  it.  The  branches  are  usually  permitted 
to  drag  upon  the  ground  in  removal,  as  the  wounded 
parts  may  be  cut  off  in  the  severe  pruning  necessary  in 
planting  large  trees  (409  c). 

Large  trees  may  be  lifted  or  lowered  to  accommodate 
grading.  A  trench  is  dug  around  the  tree,  leaving  a 
cylinder  of  earth  intact  about  the  roots.  Soil  is  then 
removed  from  beneath  one  side  of  the  cylinder  below 
the  roots  and  a  block  set  under  as  a  fulcrum.  The  top 
of  the  tree  is  then  inclined  toward  the  fulcrum  by 
means  of  a  rope,  until  the  roots  are  lifted  on  the  op- 
posite side.  If  the  tree  is  to  be  raised,  soil  is  packed 
under  the  elevated  roots,  after  which  the  top  is  tilted  in 
the  opposite  direction,  until  the  roots  are  lifted  on  the 
fulcrum  side,  when  soil  is  placed  under  as  before.  This 
process  is  repeated  until  the  tree  has  been  lifted  to  the 


Transplanting. 


239 


desired  height.     If  the  tree  is  to  be  lowered,  earth  is 
removed  at  each  tilt. 

404.  Sacking  the  Earth-Enclosed  Roots  is  practiced 
in  lifting  and  removing  orange  trees  in  California  and 
may  be  profitably  employed  with  other  evergreens.  A 
rather  deep  trench  is  dug  at  one  side  of  the  tree,  and 
.from  this  trench,  the  deeper  roots  are  severed.  The 
top  earth  is  then  removed  down  to  the  first  lateral 
roots,  when  all  the  remaining  large  roots  are  severed  at 
some  distance  from  the  trunk.  The  tree  is  next  tilted 
to  one  side  and  a  piece  of  burlap  or  matting  is  drawn 
beneath  it,  after  which  the  matting  is  folded  about 
the  earth  cylinder  and  well  tied. 

B — REMOVING    THE    PLANT. 

Plants  with  their  roots  out  of  the  soil  should  be  care- 
fully protected  from  mechanical  injury,  from  drying 
and  from  freezing.  To  insure 
such  protection,  plants  to  be 
transported  any  considerable 
distance  should  be  packed. 

405.  Plants  Packed  for 
Transportation  should  be  in- 
closed throughout,  and  the 
roots  should  be  in  close  contact 
with  some  moist  material,  pref- 
erably bog  moss.  Straw  is  often 
used  for  this  purpose  and  an- 
FIG.  129.  showing  how  swers  well  for  packing  about 

plants     should     be     packed    ,  n      ,  ,. 

for  shipping.  the    trunks    and    branches    of 

trees,  but  it  is  inferior  to  moss  for  inclosing  roots,  as 


240  Principles  of  Plant  Culture. 

it  is  more  liable  to  heat  and  does  not  so  well  retain 
moisture. 

Herbaceous  plants,  as  the  strawberry,  cabbage,  sweet 
potato,  etc.,  may  be  packed  in  layers  separated  with 
moss,  as  follows :  Over  the  bottom  of  a  box,  the  width 
of  which  is  about  twice  as  long  as  the  plants  to  be 
packed,  and  which  has  slatted  sides,  place  a  thin  layer 
of  damp  (not  wet)  moss,  and  over  this,  place  a  layer 
formed  of  a  double  row  of  the  plants,  with  their  roots 
at  the  center,  overlapping  a  little,  and  tops  toward 
the  sides  of  the  box  (Fig.  129).  Then  put  in  another 
layer  of  moss  and  so  on  until  the  box  is  full,  or  the 
desired  quantity  is  packed.  The  thickness  of  the  layers 
will  depend  upon  the  time  of  year,  the  temperature, 
the  distance  to  be  transported  and  the  kind  of  plants. 
The  warmer  the  weather,  the  thinner  should  be  the  lay- 
ers of  plants,  as  a  rule.  When  the  top  of  the  box  is 
put  on,  the  contents  should  be  pressed  sufficiently  to 
prevent  the  plants  from  shaking  out  of  place. 

406.  Puddling   the    Roots    of   Trees,    i.    e.,    dipping 
them  in  a  paste  of  soil  and  water,  is  much  practiced  by 
nurserymen  and  tends  to  prevent  them  from  drying. 
The   paste   should  be   made   with   rather   light,  loamy 
soil  and  of  the  consistency  of  cream. 

407.  Trees  are  commonly  Bundled   for  Transporta- 
tion to  economize  space.     For  this  purpose,  a  device 
resembling  a  sawbuck,  with  the  arms  cushioned  with 
burlap  or  carpeting  is  very  convenient.     The  trees  are 
laid  between  the  arms,  with  the  roots  placed  evenly  at 
one  end.     The  stems  are  then  drawn  snugly  together 
with  a  broad  strap,  after  which  they  are  bound  with 


Transplanting. 


241 


soft  cord  or  with  young  and  tender  shoots  of  the  osier 
willow.*  After  bundling,  the  space  between  the  roots 
should  be  filled  with  damp  moss,  and  the  whole  mass  of 
roots  surrounded  with  the  same  material.  If  the  dis- 
tance to  be  transported  is  short,  the  mossed  roots  may 
be  sewed  up  in  burlap  or  matting  and  the  tops  may  be 
tied  up  in  straight  straw,  or  the  whole  bundle  may  be 
inclosed  in  burlap.  If  the  distance  is  long,  the  bundle 
should  be  boxed,  to  more  effectually  prevent  the  tree 
from  damage.  The  bundles  may  be  packed  very  closely 
in  the  box  without  injury,  provided  they  nowhere  come 
in  direct  contact  with  it.  Boxed  or  bundled  trees,  that 
cannot  be  shipped  at  once,  should  be  stored  in  a  cool, 
damp  place. 

408.  Unpacking  and  Heeling-In.  Packed  plants 
should  generally  be  removed  from  their  package  as 
soon  as  they  reach  their  destination.  If  they  cannot  be 
replanted  immediately,  they 
should  be  heeled-in.  This  con- 


FIG.  130.  Nursery  trees  heeled-in  to  prevent  drying.  A,  a 
short  row  of  trees  with  only  the  roots  covered.  B,  a  row  with 
their  tops  bent  down  and  covered  with  earth  at  C.  (After  Green.) 
Sometimes  the  whole  tops  are  covered.  Trees  should  not  be 
heeled-in  in  the  bundles. 

sists  in  removing  them  from  their  bundles  and  tempo- 
rarily  planting   their   roots   in   soil    (Fig.    130).     The 


242  Principles  of  Plant  Culture. 

roots  should  be  well  covered,  and  if  at  a  dry  season, 
they  should  also  be  mulched.  To  avoid  mixing  varie- 
ties, a  separate  row  should  be  made  of  each  sort. 

Nursery  trees  that  cannot  be  packed  for  shipment  at 
the  proper  time,  are  often  lifted  and  heeled  in,  to 
retard  the  starting  of  the  buds. 


409.  Preparation  of  the  Plant,  a — Washing  the 
roots.  The  "puddled"  roots  of  nursery  trees  (406) 
are  sometimes  found  inclosed  at  unpacking  in  a  mass 
of  mud  that  is  so  compact  as  to  largely  exclude  the  air 
(Fig.  131).  The  roots  of  such 
trees  should  be  washed  clean  be- 
fore replanting  (Fig.  132). 

b — Trimming    the    roots.      The 
roots    of    trees    that    have    been 
broken  or  mangled  in  the  lifting 
or   transportation    should    be   cut 
FIG  131         FIG  132     back  to  sound  wood  with  a  sharp 

FIG.  131.  Puddled  roots    knife, 
of  nursery  tree. 

FIG.  132.     The    same       Fibrous    rooted    plants,    as    the 

washed,        ready        for 

planting.  strawberry,   are  much  more  read- 

ily planted  when  the  roots  are  trimmed,  as  shown  in 
Fig.  31. 

c — Reducing  the  top.  The  buds  of  trees  and  shrubs 
should  generally  be  reduced  in  number  at  replanting 
to  correspond  with  the  destruction  of  the  younger  roots 
during  the  lifting  process ;  otherwise  the  water  supplied 
by  the  roots  may  be  insufficient  to  open  the  buds  (62). 
This  is  best  accomplished  by  thinning  out  and  cutting 


Transplanting.  243 

back  the  branches.  As  a  rule,  it  is  better  to  reduce  the 
top  rather  sparingly  at  replanting,  with  the  expecta- 
tion of  cutting  it  back  farther  if  the  buds  do  not 
promptly  open  at  the  proper  time.  The  branches  that 


FIG.  133.  FIG.  134. 

FIG.  133.     Roots    of    tree    properly    planted. 
FIG.  134.     Same  improperly  planted. 

can  best  be  spared  should  be  removed  (420).  Failure 
to  properly  reduce  the  top  is  a  frequent  cause  of  death 
or  loss  of  vigor  in  transplanted  trees.  Small  plants  in 
leaf,  as  the  strawberry,  cabbage,  etc.,  usually  endure 
transplanting  better  if  their  larger  leaves  are  removed 
at  replanting. 

d— Wetting  the  roots  just  before  replanting  is  quite 
important,  as  it  favors  intimate  contact  with  the  soil 
particles. 

Plants  that  have  suffered  from  loss  of  moisture  in 
transit  should  have  their  roots  soaked  in  clean  water  for 
a  few  hours  before  replanting.  Deciduous  trees  of 
which  the  bark  is  considerably  shriveled  may  often  be 
saved,  if  the  center  of  the  buds  is  still  fresh,  by  burying 
ihtm  in  moist  earth  until  the  bark  resumes  its  plump- 
ness. 


244  Principles  of  Plant  Culture. 

410.  Replanting  the  Roots.  The  object  to  be  at- 
tained in  this  operation  is  to  place  moist  and  well-aer- 
ated, soil  in  contact  with  all  of  the  roots  of  the  plant. 
The  roots  should  also  be  placed  at  about  the  same 
depth,  and  in  nearly  the  same  position  that  they  grew 
before  the  removal. 

Fig.  133  shows  the  roots'  of  a  tree  properly  planted. 
The  hole  was  dug  sufficiently  large  so  that  the  roots 
were  readily  placed  in  it  without  crowding,  and  the 
soil  was  so  well  worked  in  among  the  roots  that  it 
comes  in  contact  with  their  whole  surface. 

Fig.  134  shows  the  roots  of  the  same  tree  improperly 
planted.  The  hole  was  dug  so  small  that  the  roots  were 
necessarily  crowded  out  of  their  nat- 
ural position,  and  the  earth  was 


FIG.  136.  FIG.  137. 

FIG.  135.     Strawberry    plant    too    deeply    planted. 
FIG.  136.     The   same  planted  too  shallow. 
FIG.  137.     Strawberry   plant   properly   planted. 

thrown  in  so  loosely  that  it  comes  in  contact  with  only 
a  part  of  the  root  surface.  Distortion  of  the  roots 
of  trees  and  shrubs  at  planting  may  cause  injurious 
root  galls. 

In  planting  trees  of  which  the  roots  are  not  already 
inclosed  in  soil  (403),  the  hands  should  be  freely  used 
to  bring  the  soil  in  contact  with  the  whole  root  surface, 


Transplanting. 


245 


and  the  earth  should  be  moderately  packed  about  the 
roots  with  the  feet,  or  otherwise. 

If  the  soil  is  dry,  it  is  probably  better  to  moisten  it 
before  placing  it  about  the  roots,  rather  than  after,  as 
we  have  then  a  better  opportunity 
to  judge  of  the  quantity  of  water 
required,  and  the  soil  is  less  likely 
to  settle  away  from  the  roots. 

Trees  of  considerable  size  should 
generally   be   staked  or   otherwise 
supported  after  planting,  to  pre- 
vent shaking  by  wind   (Fig.  138). 
Surrounding  the  trunk  with  poor- 
conducting  material  as  hay,  straw 
or  canvas,  tends  to  prevent  dam- 
age from  sun-scald  (185), to  which 
recently-transplanted     trees 
are  especially  liable;  as  the 
evaporation  stream    (77)    is 
much     reduced,     the     bark 
tends     to     become     unduly 
heated. 

411.  Devices  for  Transplanting.  With  young  trees 
and  plants,  that  possess  abundant  vigor,  rapidity  of 
planting  is  often  of  greater  importance  than  the  ob- 
servance of  precise  rules.  In  this  case,  that  method  is 
best  which  secures  a  given  number  of  transplanted  and 
vigorously-growing  plants  at  the  least  cost.  The  trans- 
planting devices  shown  in  Figs.  139-141  aid  greatly  in 
accomplishing  this  end. 


FIG.  138.  Large  transplanted 
tree  wound  with  hay  rope  and 
supported  by  wires. 


246 


Principles  of  Plant  Culture. 


The  dibber  (Fig.  139)  is  perhaps,  aside  from  the 
spade,  the  most  valuable  single  tool  for  transplanting. 
It  is  used  for  opening  the  hole  to  receive  the  roots  of 

small  plants,  as  cab- 
celery,  onions, 
etc.,  and  for 
pressing  earth 
about  the 
roots  ;  it  an- 
swers equally 
well  for  plant- 
i  n  g  cuttings 
and  root 

FIG.  139.  FIG.  140.  FIG.  141.     &****'  ^ 

FIG.  139.     Flat   steel  dibber   (one-sixth  natural  manner   of    US- 

FIG.  140.     Tool    for    planting    root    grafts    and  m&   ^    aPPears 
cuttings   (much  reduced). 


FIG.  141.    Richards'    transplanting    tools,    made  ' 

by  F.   Richards,    Freeport,   N.  T.  and    144. 

Fig.  140  shows  a  very  convenient  tool  for  planting 
root  grafts  and  cuttings.  It  consists  of  six  steel  dibbers, 
attached  in  a  line  to  a  piece  of  scantling,  at  the  distance 
with  a  handle  affixed  above.  In  using  this  tool,  the 
operator  crowds  the  dibbers  into  the  soil  with  the  foot, 
guided  by  a  line.  He  then  moves  the  frame  to  and  fro 
until  the  holes  are  sufficiently  opened,  when  he  with- 
draws the  dibbers  by  lifting  the  frame,  and  pases  on  to 
repeat  the  operation.  A  person  follows  inserting  the 
grafts  or  cuttings,  and  crowding  earth  about  them  with 
the  ordinary  dibber. 

Fig.  141  shows  a  set  of  transplanting  tools,  useful  in 
removing  a  limited  number  of  plants  that  are  not 


Transplanting.  247 

closely  crowded  and  that  need  to  be  carried  but  a  short 
distance.     They  are  especially  useful  for  transplanting 
strawberry  plants  during  summer  and  autumn.     These 
tools  and  also  the  Baldridge 
transplanter  enable  the  plant 
to   be   readily   lifted  with   a 
cylinder    of    earth    and    re- 
planted in  a  hole  just  large 
enough  to  receive  the  latter. 
Fig.   142  shows  a  success- 
ful machine  for  planting  to- 
bacco,    cabbage,     strawberry 
and    other    low,    herbaceous 
ft*    *  tt^gy    plants.      It    plants   these    as 


FIG.  142. 

er,    made  by  Full 
Manufacturing     Co., 
Wis. 


Madison, 


liver  them  to  it  in  the  proper 
position,  and  waters  the  soil  about  the  roots  at  the  same 
time. 

412.  Potting  and  Shifting.  Potting  is  the  act  of 
planting  plants  in  greenhouse  pots. 

The  pots  should  be  clean  and  are  usually  dipped  in 
water  before  receiving  the  plants,  until  they  have  ab- 
sorbed as  much  of  the  liquid  as  they  will  take  without 
leaving  any  upon  the  surface.  Rooted  cuttings  are 
generally  potted  in  pots  one  and  one-half  to  two  inches 
in  diameter,  and  the  plants  are  changed  to  larger  pots 
(shifted}  as  the  roots  require  more  room.  Pots  three 
inches  or  more  in  diameter  are  commonly  filled  one- 
third  full  or  less  with  pieces  of  broken  pots  (potsherds) 
to  insure  abundant  drainage,  and  these  are  often  cov- 
ered with  a  little  spagnum  moss  before  putting  in  the 


248 


Principles  of  Plant  Culture. 


soil.  The  soil  used  for  petting  should  be  of  a  sort  that 
does  not  harden,  ''bake,"  on  drying,  and  should  gener- 
ally be  liberally  supplied  with  plant  food.  Decayed 
sods  from  an  old  pasture,  leaf  mold,  decomposed  ma- 
nure, and  sand,  the  whole  mixed  and  sifted  through  a 
coarse  sieve,  form  a  good  potting 
soil.  The  proportions  of  the  differ- 


FIG.  143. 

Showing  manner  of  using  the  dibber  in  planting. 

FIG.  143.     Inserting   roots    in   the  hole  opened   by   dibber. 

FIG.  144.     Pressing  earth  about  roots  with  the  dibber. 

ent  ingredients  used  vary  with  different  plants.  The 
soil  should  be  moderately  moist,  and  should  be  closely 
pressed  about  the  roots.  The  details  of  potting  are 
shown  in  Figs.  145  to  148. 

Shifting  is  the  changing  of  a  plant  from  one  pot  to 
another,  usually  a  larger  one.  Plants  in  small  pots  are 
generally  shifted  as  often  as  their  roots  begin  to  crowd, 
and  the  shifting  is  continued  as  long  as  further  growth 
is  expected.  When  bloom  is  desired,  the  pots  are  per- 
mitted to  become  filled  with  roots  (135). 


Transplanting. 


249 


The  pots  into  which  plants  are  to  be  shifted  should 
be  prepared  as  directed  for  potting.  A  little  potting 
soil  is  placed  in  the  bottom  of  the  pot,  or  over  the 


FIG.  145.  FIG.  146. 

FIG.  145.  The  workman  takes  the  pot  in  his  left  hand,  and  at 
the  same  time  a  handful  of  potting  soil  in  the  right  hand. 

Fia.  146.  He  places  the  soil  in  the  pot,  pressing  it  against  one 
side  with  the  right  hand,  while  he  picks  up  a  plant  with  the  left 
hand. 

drainage  material,  after  which  the  plant  to  be  shifted 
is  tipped  out  of  its  pot,  by  inverting  the  latter,  placing 
the  hand  upon  the  surface  of  the  soil,  to  support  it,  and 
tapping  the  rim  of  the  pot  gently  upon  the  edge  of  the 
potting  bench. 

If  the  soil  is  in  proper  condition,  it  will  readily  slip 
out  of  the  pot  intact,  after  which  it  should  be  placed  in 
the  center  of  the  new  pot  and  the  space  about  it  filled 
with  potting  soil  moderately  pressed  down.  The  roots 
of  woody  plants  should  not  be  covered  deeper  than 
they  grew  before  the>  shifting.  See  Figs.  150,  151  and 
152. 


250  Principles  of  Plant  Culture. 

D— AFTER-CARE  OF  TRANSPLANTED   STOCK. 

413.  Mulching  the  soil  about  transplanted  plants 
(232)  is  very  important  in  localities  subject  to  drought. 
As  a  rule,  it  is  wise  to  apply  the  mulch  immediately 
after  transplanting,  but  with  trees  transplanted  very 


Fia.  147.  Placing  the  roots  of  the  plant  against  the  soil  in  the 
pot  with  the  left  hand,  he  takes  another  handful  of  soil  with  the 
right  hand. 

FIG.  148.  He  fills  the  remaining  space  in  the  pot  with  soil  and 
presses  it  down  with  the  thumbs,  tapping  the  pot  gently  upon  the 
bench  in  the  meantime. 


early  in  spring,  it  is  better  to  defer  mulching  until  the 
soil  becomes  sufficiently  warm  to  promote  root  absorp- 
tion (101). 

Watering  recently-transplanted  plants  requires  dis- 
cretion. As  a  rule,  mulching  is  preferable  to  watering, 
but  if  mulching  proves  insufficient,  watering  is  the  last 


Transplanting. 


251 


resort.  In  this  case,  the  soil  about  the  roots  should  be 
saturated  with  water  and  should  not  be  permitted  to 
become  dry  again  until  growth  starts.  A  hole  may  be 
made  in  the  soil  about  the  roots  and  kept  filled  with 
water  until  the  liquid  ceases  to  soak  away  rapidly,  after 

which   it   should   be   occasionally   filled 

until  growth  commences. 

414.  Shading  plants  transplanted  in 
leaf,  until  the  roots  resume  activity,  is 
important   (235).     Evergreen  trees  and 
shrubs  may  often  be  shaded  with  bar- 
rels or  boxes,  or  with  boughs  from  other 
evergreen  trees. 

415.  Tardy     Starting    into     Growth 
after  transplanting  is  usually  evidence 
that  the  roots   are   not  supplying  suf- 
ficient water.     In  such   cases,   if  other 
precautions   have   been    observed,    it   is 
well  to  further  reduce  the  top.     Plants 
in    this    condition    may    sometimes    be 

£  saved  by  wrapping  the  stem  in  oiled  or 
rubber  cloth  to  check  loss  of  moisture, 
Devicf  for  starting  or  witn  straw  or  moss  which  may  be 

growth  in  trees.         wet   f requent]y  tjU  growth  starts. 

The  device  shown  in  Fig.  149  often  causes  recently 
planted  trees  to  start  growth  that  seem  likely  to  fail 
without  it.  It  consists  of  a  flask  or  bottle  containing 
distilled  or  rain  water,  supported  a  few  feet  above  the 
ground  and  connected  by  a  rubber  tube  with  the  cut-off 
end  of  a  root,  as  shown.  If  the  inverted  flask  is  used, 


252  Principles  of  Plant  Culture. 

a  short  tube  B  B  should  extend  through  the  cork  and 
to  near  the  bottom  of  the  flask,  to  admit  air. 


Fig.  160  Fie.  151  Fig.  152 


PIG.  150.  A  poorly-potted  plant.  No  provision  is  made  for 
drainage;  the  pot  is  filled  to  the  top  with  soil,  leaving  no  space 
to  receive  the  water;  and  the  stem  of  the  plant  is  not  at  the 
center  of  the  pot. 

FiG.  151.      A  well-potted  plant.    A,    potsherds;    B,    moss. 

PIG.  152.  A  poorly -fhif ted  plant.  C,  open  spaces  due  to  In- 
sufficient pressing  of  the  soil. 

Flower-buds  should  generally  be  removed  from  re- 
cently-transplanted plants  (139). 

SECTION  III.    PR'UNING. 

416.  Pruning  is  the  removal  of  a  part  of  a  plant,  in 
order  that  the  remainder  may  better  serve  our  purpose. 

The  parts  of  plants,  being  less  highly  specialized  than 
those  of  animals,  may  be  removed  with  less  damage  to 
the  individual  than  is  possible  with  animals,  except  in 
the  lowest  types. 

The  word  pruning,  as  commonly  used,  applies  chiefly 
to  the  removal  of  parts  of  woody  plants  with  the  knife, 
shears  or  saw,  but  the  operations  defined  below  prop- 
erly come  under  the  same  head. 

a— Pinching  is  the  removal  with  the  thumb  and  fin- 
ger  °f  the  undeveloped  nodes  at  the  terminus  of  grow- 
ing shoots,  in  order  to  check  growth. 


Pruning.  253 

b— Trimming  or  dressing,  when  applied  to  young 
nursery  stock,  is  the  shortening  of  both  roots  and  stem, 
preparatory  to  planting  in  nursery  rows.  The  roots 
are  shortened  to  facilitate  planting,  and  the  stems  are 
shortened  to  reduce  the  number  of  buds  (409  c). 

c— Topping  is  the  removal  of  the  flower  stalk,  as  in 
tobacco,  to  prevent  exhaustion  of  the  plant  by  the  for- 
mation of  seed. 

d — De  tasseling  is  the  removal  of  the  staminate  flow- 
ers (tassels)  of  undesirable  plants  of  Indian  corn,  to 
prevent  pollination  from  them  (150). 

e—Suckering  is  the  removal  of  shoots  that  start  about  )  C 
the  base  of  the  stem,  or  in  the  axils  of  the  leaves,  as 
in  Indian  corn  or  tobacco.     Its  object  is  to  prevent  ex- 
haustion  of  the   plant  by  the  production  of  needless 
shoots. 

f— Disbudding  is  the  removal  of  dormant  buds,  to 
prevent  the  development  of  undesirable  shoots. 

g— Ringing  is  the  removal  of  a  narrow  belt  of  bark 
about  a  branch,  to  obstruct  the  current  of  prepared 
food  (138). 

h— Notching  is  the  cutting  of  a  notch  just  above  or 
below  a  bud  or  twig  to  modify  its  growth. 
\  A— ^Thinning  fruit  is  the  removal  of  a  part  of  the 
'fruits  upon  a  plant,  to  permit  the  remaining  ones  to 
attain  larger  size,  and  to  prevent  exhaustion  of  the 
plant  by  excessive  seed  production. 

j — Deflowering  or  defruiting  is  the  removal  of  flower- 
buds  or  fruits  to  prevent  exhaustion  of  the  plant  (139). 

k — Root  pruning  is  the  shortening  of  the  roots  of 
plants  in  the  soil,  to  check  growth,  or  to  stimulate  the 
formation  of  branch  roots  nearer  the  trunk  (104). 


254  Principles  of  Plant  Culture. 

I— Sprouting  is  the  removal  of  sterile  shoots  or  water 
sprouts  from  the  upper  part  of  the  grape  vine. 

417.  The  Season  for  Pruning.     The  milder  kinds  of 
pruning,   as    pinching    and    disbudding,  may  be    per- 

!<^  t- formed  whenever  the  necessity  for  them  appears.  But 
in  perennial  plants,  severe  pruning,  as  the  removal  of 
branches  of  considerable  size,  is  generally  least  inju- 
rious if  performed  during  the  dormant  period.  As  the 
exposure  of  unhealed  wounds  may  cause  damage  from 
drying,  and  invites  infection  by  injurious  fungi  (320), 
severe  pruning  is  commonly  best  performed  toward  the 
end  of  the  dormant  period,  i.  e.,  in  early  spring  be- 
cause healing  is  most  rapid  at  the  beginning  of  the 
growing  season  (72).  Pruning  should  not,  however, 
be  done  at  a  time  when  sap  flows  freely  from  wounds, 
as  this  tends  to  waste  reserve  food.  In  plants  subject 
!  to  this,  as  the  maples  and  grape,  pruning  is  probably 
best  performed  just  before  or  just  after  the  sap-flowing 
period. 

418.  Where   and  How  should  the  Cut  be  Made  in 
Pruning?     Since  the   movement   of   prepared   food   is 
mainly  from  the  leaves  toward  the  root  (80),  it  follows 
that  when  a  branch  is  cut  off  at  some  distance  from  the 
member  that  supports  it,  the  wound  usually  will  not 
heal,  unless  there  are  leaves  beyond  the  wound  to  man- 
ufacture food,  and  thus  make  a  growth  current  possi- 
ble   (72).     The   cut   should,   therefore,  be  made  close 
enough  to  the  supporting  member  so  that  it   can   be 

0  "L  healed  from  the  cambium  of  the  latter.  In  woody 
plants,  there  is  usually  a  more  or  less  distinct  swelling 
about  the  base  of  a  branch  (Fig.  153),  produced  by  the 


Pruning. 


255 


cambium  of  the  supporting  member  and  just  beyond 
this  swelling,  a  more  or  less  distinct  line  marks  the 
point  where  the  cambium  of  the  branch  and  of  the  sup- 
porting members  unite.  In  a  healthy  tree,  a  wound 
made  by  a  branch  of  reasonable  size,  cut  off  at  this 


FIG.  153.  FIG.  154.  FIG.  165. 

FIG.  153.  Showing  the  proper  place  to  make  the  cut  in  prun- 
ing. A  wound  made  by  a  cut  on  the  dotted  line  A-B  will  be 
promptly  healed.  One  made  on  the  line  C-D  or  E-F  will  not. 
In  Fig.  154  the  lower  branch  was  cut  off  too  far  from  the  trunk. 

FIG.  154.  Showing  how  to  make  the  cut  in  pruning  large 
branches.  The  upper  cut,  all  made  from  above,  permits  the  branch 
to  split  down.  The  left  cut,  first  made  partly  from  below,  pre- 
vents splitting  down. 

FIG.  155.  Pruning  to  an  outside  or  inside  bud.  Cut  as  In  the 
figure,  the  uppermost  bud  would  form  a  shoot  that  tends  to  ver- 
tical. Cut  on  the  dotted  line,  the  uppermost  bud  would  form  a 
shoot  tending  to  horizontal. 

line,  will  usually  heal  promptly,  but  if  the  cut  is  made 
much  farther  out,  it  will  not. 

The  cut  should  generally  be  made  at  right  angles 
with  the  branch,  rather  than  parallel  to  the  supporting 
member,  since  it  is  important  that  the  wound  be  no 
larger  than  is  necessary.  Wounds  so  large  that  they 
cannot  heal  promptly  should  be  painted  with  lead  and 
oil  paint  to  preserve  the  wood. 

419.  Unhealed  Wounds  Introduce  Decay  into  the 
heartwood  of  trees.  Since  the  cells  of  the  heartwood 


256  Principles  of  Plant  Culture. 

form  a  congenial  field  for  certain  destructive  fungi 
(321),  that  having  once  gained  entrance,  sooner  or 
later  destroy  the  heartwood  of  the  whole  trunk,  thus 
greatly  weakening  it  and  preparing  the  way  for  the 
final  destruction  of  the  tree. 

420.  Objects  of  Pruning.  If  intelligently  performed, 
pruning  has  one  of  four  objects  in  view,  viz. : 

a — To  change  the  form  of  the  plant,  as  to  outline  or 
density  (formative  pruning}. 

b — To  stimulate  development  in  some  special  part,  as 
to  promote  the  growth  of  wood  or  the  formation  of 
flower-buds  (stimulative  pruning.} 

c — To  prevent  some  impending  evil  to  the  plant,  as 
to  arrest  or  exclude  disease  (protective  pruning). 

d — To  hasten  or  retard  maturity  (maturative  prun- 
ing). 

A — FORMATIVE    PRUNING. 

This  aims  to  regulate  the  form  of  the  plant  with 
reference  to  outline  or  density,  or  to  strength  of  stem. 
Pruning  for  outline  includes  pruning  (a)  for  symmetry 
or  picturesqueness ;  (b)  for  stockiness  or  slenderness. 

421.  Pruning  for  Symmetry  aims  to  develop  in  the 
plant  a  head  that  is  symmetric  with  reference  to  its 
trunk.     The  general  principle  involved  is  the  suppres- 
sion of  growth  in  all  parts  that  tend  to  grow  beyond 
the  lines  of  symmetry  (Fig.  156).     This  is  best  accom- 
plished by  pinching  (416  a)  during  the  growth  period, 
thus   economizing   the    plant's   energy;   but   when   the 
pinching  has  been  neglected,  the  shoots  that  grew  out 


Pruning. 


257 


of  symmetry    may   be    cut   back   during   the   dormant 
period. 

In  pruning  for  symmetry,  the  plant  should  generally 
be  encouraged  to  develop  the  form  that  is  natural  to 
the  particular  species  or  variety,  e.  g.,  the  American 
elm  tree,*  which  naturally  develops  an  open,  some- 


FIG.  156.  Pruning  for  symmetry.  The  branches  growing  be- 
yond the  ideal  outline,  indicated  by  the  dotted  line,  should  be  cut 
off  at  the  points  indicated. 

what  spreading  head,  tending  to  be  broadest  toward 
the  top,  should  not  be  pruned  to  the  same  form  as  the 
sugar  maplef  that  develops  a  more  roundish  and  com- 
pact head.  Evergreens  are  sometimes  pruned  to  ideal 
forms,  as  in  topiary  work,  a  practice  that  is  generally 
condemned  by  good  taste. 

*  Ulmus  Americana.          f  Acer  saccharinum. 


.258 


Principles  of  Plant  Culture. 


422.  Pruning    for    Picturesqueness    is    seldom    em- 
ployed.    It  requires  a  thorough  knowledge  of  pruning 
and  of  plant  growth,  combined  with  the  conceptions  of 
the  artist.    «^- 

423.  Pruning  for  Stockiness  aims  to  develop  a  low 

head,  with  abundant 
branching,  and  a  strong 
trunk.  It  is  best  accom- 
plished by  pinching 
(416  a)  the  uppermost 

>#^ v     growing    points    during 

jr  \  the  growth  period,  and 

l^"     \         encouraging  low  branch- 
ing on  the  stem.     If  a 


Fio.  157.  Raspberry  cane 
rendered  stocky  by  prun- 
ing. 

spreading    form    is    de-     CanlGno\5pVuSd.pbe 

sired,  the  lower  branches 

should    be    pruned   to    outside    buds   (Fig.    155). 

Pruning  for  stockiness  is  much  practiced  in  the 
raspberry  (Figs.  157  and  158)  and  blackberry, 
in  hedges  and  in  many  ornamental  plants.  It 
tends  to  the  production  of  flower-buds,  by  check- 
ing growth  of  wood  (136)^L 

424.  Pruning  for  Slenderness  is  seldom  neces- 
sary, as  a  slender  growth  may  readily  be  produced  by 
close  planting.     It  is  accomplished  by  persistently  re- 


Pruning. 


259 


moving  or  cutting  back  the  lower  branches,  and  per- 
mitting only  a  few  branches  to  develop  near  the  ter- 
minus of  the  stem. 

425.  Pruning  for  Den- 
sity applies  either  to  in- 
creasing or  decreasing  the 
density  of  the  head.  In 
ornamental  and  shade 
trees,  a  compact  head  is  FIG.  159.  Showing  how  to  disbud 

shoots  of  some  coniferous  trees, 
often  desirable  while  in  Picking  out  the  terminal  bud  A 

in  spring  usually  causes  both  the 
fruit  trees,  a  head  that  adjacent  lateral  buds  to  develop. 

admits  abundant  light  and  air  (Fig.  162)  is  important 
(242).  To  increase  density,  encourage  lateral  branch- 
ing by  pinching 
all  the  more 
prominent  ter- 
minal growing 
points  (Fig. 
160).  In  some 
coniferous  trees, 
as  the  Norway 
-spruce,*  disbud- 
of  the  terminal  shoots 
(Fig.  159)  in  spring  is  advis- 
able, and  in  woody  plants  too 
FIQ.  leo.  showing  how  den-  tall  f  or  pinching,  the  more 

sity    of    growth    is    promoted 

(right-hand  side)  by  persist-  prominent    terminal    growing 

ent  pinching   of    the   terminal  i 

growing  points.  points  may  be  cut  back  with 

the  pole  shears  (431),  which  causes  the  head  to  grow 
more  dense. 


260 


Principles  of  Plant  Culture. 


In  pruning  to  form  an  open  head  (Fig.  162),  it  is 
wiser,  as  a  rule,  to  thin  out  the  smaller  branches  at 
some  distance  from  the  trunk  than  to  remove  large 
branches  at  their  union  with  the  trunk.  The  clearer 
the  atmosphere  in  a  given  locality,  the  less  thinning 
of  the  top  is  required  to  produce  the  maximum  number 
of  fruit  buds  (243). 


«l       r 


FIQ.  161.     Unpruned   apple   tree,   with   hea< 
light. 


426.  Pruning  for  Strength,  a— of  the  Trunk.  Trees 
and  plants  grown  in  closely-planted  nursery  rows  often 
have  trunks  insufficiently  developed  to  support  the 
head,  when  planted  by  themselves.  To  remedy  this  de- 
fect, we  promote  the  formation  of  new  vascular  bun- 


Pruning.  261 

dies  (67,  123)  by  inducing  branching,  which  we  ac- 
complish by  cutting  back  the  top  in  proportion  to  the 
slenderness  of  the  trunk  (423). 

b— of  the  Branches.  Trees  expected  to  support  heavy 
crops  of  fruit,  or  to  endure  high  winds,  should  have 


FIG.  162.     Apple    tree    pruned    with   open   head,    to   admit  abun- 
dant  light. 

branches  developed  with  special  reference  to  strength^ 
In  such  cases,  several  medium  to  small  branches  are 
better  able  to  endure  the  strain  than  a  few  large  ones 


262 


Principles  of  Plant  Culture. 


(245b),  and  the  loss  to  the  tree  of  a  small  branch, 
should  it  occur,  is  less  serious  than  that  of  a  large  one. 
Forming  the  head  of  fruit  trees  of  three  or  four  main 
branches  is  to  be  discouraged  for  this  reason.  Several 
small  branches  from  a  common  trunk  are  better,  and 
these  should  be  encouraged  to  leave  the  trunk  at  nearly 
right  angles  (Fig.  155).  Forks  in  the  trunk  of  fruit 
trees,  dividing  the  wood  into  two  nearly  equal  parts 
are  objectionable,  as  one  or  the  other  part  is  very  liable 
to  split  down  under  the  weight  of  a  heavy  fruit  crop. 

Main  branches  inclined  to  split  down  may  sometimes 
be  prevented  from  doing  so,  by  twisting  two  smaller 
branches  together,  to  form  a  connection  between  them 
(Fig.  163).  The  branches  thus 
twisted  often  grow  together,  form- 
ing a  tie  of  great  strength.  A  main 
branch  that  has  actually  com- 
menced to  split  down  may  often 
be  saved  by  passing  an  iron  bolt 
through  it  and  the  remainder  of 
the  trunk.  A  bolt  thus  inserted 
may  become  entirely  inclosed  by 
later  growth. 

"S# 

B — STIMULATIVE    PRUNING. 
ofFf?uit16treeBtitSCto!         ™S    dePends   UP°n   the    Principle 

formed  *lt  NwfsTe"  that  th°  ™PP™ssion  of  growth  in 
twlgs-  one  direction  tends  to  stimulate  it 

in  others.  Stimulative  pruning  may  be  employed  either 
to  stimulate  growth  of  leaves,  branches  and  roots,  or 
of  flower-buds. 


Pruning.  263 

427.  a— Pruning  for  Growth  may  be  performed,  (a) 
By  removing  a  part  of  the  branches,  thus  reducing  the 
number  of  growing  points  and  the  surface  exposed  to 
evaporation.     Plants  that  are  not  making  satisfactory 
growth  through  feeble  root   action,  may  often  be  in- 
vigorated by  this  treatment,  which  is  especially  useful 
in   trees  recently   transplanted   or   weakened  by  over- 
bearing. 

(b)  By  suppressing  reproduction.  When  growth  is 
desired,  it  is  often  advisable\to  prevent  the  develop- 
ment of  flowers.  Newly  planted  strawberry,  raspberry 
and  blackberry  plants  usually  make  better  growth  the 
first  season  if  the  flower-buds  are  picked  off.  The  re- 
moval of  flowers  in  the  potato  plant  tends  to  stimulate 
the  growth  of  tubers,  especially  in  varieties  that  form 
seed.  The  removal  of  flower-buds  from  cuttings  in  the 
propagating  bed  encourages  the  formation  of  roots. 
Topping  tobacco  and  rhubarb  plants  (416  c)  causes 
the  leaves  to  grow  larger,  and  of  onion  plants  stimu- 
lates growth  of  the  bulbs.  De-tasseling  corn  encourages 
growth  of  the  ears  (416  d).  Thinning  fruit  on  plants 
that  incline  to  overbear,  causes  the  remaining  fruits 
to  grow  larger  (416  i,  159)X 

428.  b— Pruning  for  Flowers  or  Fruit.  Since  check- 
ing growth  tends  to  stimulate  the  formation  of  flower- 
buds  (134  b),  we  encourage  flowering  in  plants  that  in- 
cline to  luxuriant  growth,  by  pruning  which  tends  to 
check  vigor.     This  may  be  accomplished, 

(a)  By  pinching  the  terminal  buds  during  the 
growth  period,  as  is  often  practiced  upon  tardy -bearing 
fruit  trees  or  upon  seedling  fruit  trees  of  which  it  is 


264  Principles  of  Plant  Culture. 

desirable  to  soon  learn  the  quality  of  the  fruit.  To  be 
successful,  it  must  be  performed  rather  early  in  the 
growing  season,  and  before  the  time  for  the  formation 
of  flower-buds.  The  blossoms  do  not  usually  appear 
until  the  season  following  the  pinching. 

With  plants  that  flower  at  the  terminal  growing 
points  of  the  principal  branches,  as  the  spiraeas,  hy- 
drangeas, rhododendrons,  etc.,  pinching  to  promote 
flowering  is  not  advisable,  as  it  tends  to  reduce  the 
size  of  the  flower  clusters.  , 

(b)  By  cutting  back  the  new  growth.    Woody  plants 
that  flower  on  stems  more  than  one  year  old,. as  the 
apple,  pear,  currant,  etc.,  when  grown  on  rich  or  well 
cultivated    ground,  or    that    have    been    too  severely 
pruned,  often  tend  to  produce  an  excess  of  new  wood 
with  a  very   feeble    development   of    flower-buds.     In 
such  cases,  it  is  advisable  to  equalize  the  growth  by  a 
moderate  cutting  back  of  all  the  young  shoots.     This 
must,  however,  be   done  with  judgment.     If  the  cut- 
ting back   is  too  severe,  it  will  stimulate   more  wood 
growth  rather  than  the  development  of  flower-buds.^ 

(c)  By  root  pruning.     This  checks  growth  by  reduc- 
ing the  number  of  root-tips,  and  thus  cuts  off  a  part  of 
the  water  supply.     It  is  applicable  to  the  same  cases  as 
pinching,  and   is  accomplished  by  cutting  off  the  ex- 
tremities of  the  roots  by  inserting  the  spade  in  a  circle 
about  the  plant,  or  in  the  case  of  trees  of  considerable 
size,  by  digging  a  trench  sufficiently  deep  to  sever  the 
lateral  roots.     The  severity  of  the  root  pruning  advis- 
able will  depend  upon  the  vigor  of  the  growth  it  is  de- 
sired to  check. 


Pruning.  265 

(cl)  By  obstructing  the  growth  current.  This  is  ac- 
complished by  ringing  (416  g),  by  notching  (416  h) 
and  by  peeling  the  stem  (72). 

When  ringing  is  practiced,  the  width  of  the  belt  of 
bark  removed  should  usually  not  be  so  great  that  the 
wound  cannot  heal  over  the  same  season  by  the  callus 
formed  on  the  upper  edge  of  the  ring  (79),  and  it  must 
be  made  sufficiently  early  to  give  time  for  healing.  A 
wider  ring  will  sometimes  heal  if  the  ringing  tools  are 
not  inserted  deeper  than  the  cambium  layer  (80).  In 
the  grape  vine,  in  which  ringing  is  often  practiced  to 
increase  the  size  and  earliness  of  the  fruit,  the  width 
of  the  belt  removed  is  less  important,  since  the  canes 
that  have  borne  fruit  are  generally  removed  in  the 
annual  pruning.  But  in  fruit  trees,  the  belt  of  bark 
removed  should  not  much  exceed  one-eighth  inch  in 
width.  Simply  cutting  through  the  bark  with  the 
pruning  saw  often  accomplishes  the  desired  endv 

Notching  above  or  below  a  bud  or  twig  affects  it  much 
as  ringing  affects  the  entire  ringed  member.  Notching 
below  a  bud  or  twig,  therefore,  checks  its  growth,  and 
is  often  followed  by  fruiting  in  that  part. 

Peeling  the  stem  has  sometimes  been  practiced  to 
make  barren  trees  fruitful  (72).  It  is  a  hazardous 
operation  at  best,  and  should  only  be  used  as  a  last 
resort.  It  is  accomplished  by  making  two  cuts  around 
the  trunk,  usually  several  inches  apart,  and  just 
through  the  bark,  with  one  or  more  vertical  cuts  be- 
t  \\ven  them,  after  which  the  bark  between  the  circular 
cuts  is  carefully  peeled  off.  It  should  only  be  per- 
formed during  a  period  of  very  rapid  growth,  and  at 

18 


266  Principles  of  Plant  Culture. 

a  time  when  the  wood  is  well  supplied  with  reserve 
food,  i.  e.,  some  time  after  the  tree  has  put  out  leaves. 
It  is  most  likely  to  succeed  in  warm,  dry  weather,  and 
when  the  wound  is  not  shaded  after  peeling;  otherwise, 
injurious  fungi  are  apt  to  infect  the  ruptured  cells.  _ 

C— PROTECTIVE    PRUNING. 

429.  Dead  or  Dying  Members  of  a  plant  Should  Be 
Promptly  Removed,  since  they  more  or  less  endanger 
its  well-being.     Dead  branches  of  any  considerable  size 
invite  decay  into  the  stem  which  often  results  disas- 
trously (419).     Branches  that  are  dying  from  infection 
by  a  fungous  parasite,  as  the  apple  or  pear  blight,  or 
the  black  knot  of  the  plum   (323),  are  especially  dan- 
gerous and  should  always  be  removed  as  soon  as  dis- 
covered.    Branches   that   tend   to     interfere    with   the 
growth  of  others  already  formed  should  be  checked  by 
pinching  (416  a),  and  those  that  interfere  by  too  close 
contact  should  be  cut  back  in  proportion  to  the  inter- 
ference. 

Scraping  off  the  dead  bark  scales  from  old  fruit  trees 
tends  to  remove  certain  destructive  insects  or  their 
eggs.  It  should  be  done  during  the  growing  season, 
and  a  short-handled  hoe  or  a  box-scraper  is  convenient 
for  the  work.  Trees  subject  to  sun-scald  should  gener- 
ally not  be  scraped  unless  other  trunk  protection  is 
given. 

D — MATURATIVE    PRUNING. 

430.  a — Pruning  to  hasten  maturity.     This  is  seldom 
practiced.     In  nursery  trees  that  tend  to  grow  too  late, 
and  are  thus  subject  to  winter  killing,  the  leaves  are 


Pruning. 


267 


sometimes  removed  two  or  three  weeks  before  the  time 
when  hard  frosts  are  expected,  to  encourage  ripening 
of  the  wood. 

The  later  tobacco  plants  in  a  plantation  are  usually 
topped  at  the  time  the  main  crop  is  pushing  the  flower 
stalk,  which  causes  their  leaves  to  mature  in  season  to 
be  harvested  with  the  rest  of  the  crop. 

b — Pruning  to  retard  maturity,  see   (158). 

431.  The  Principal  Pruning  Implements  are  the 
following : 

The  pruning  knife.  (Fig.  164)  is  useful  for  removing 
small  woody  shoots.  The  blade  should  be  of  good  steel, 
and  the  point  should  curve  forward 
a  little,  to  prevent  the  edge  from 


FIG.  166. 


FIG.  167. 


FIG.  164.     Pruning  knife.    FIG.  165.     Pruning  saw. 

FIG.  166.     Pruning  shears.  FIG.  167.     Hedge  shears  (much  reduced). 

slipping  off  the  branch.  The  handle  should  be  large  to 
avoid  blistering  the  hand,  the  base  of  the  blade  should 
be  thick  to  furnish  support  for  the  thumb,  and  the  rivet 


268 


Principles  of  Plant  Culture. 


should  be  strong  enough  to  sustain  hard  pressure  upon 
the  handle. 

In  using  the  pruning  knife,  the  shoot  to  be  cut  off 
should  generally  be  pressed  with  one  hand  toward  the 
member  that  supports  it  and  the  blade  should  be  in- 
serted at  the  proximal  side.  Care  is  necessary  to  pre- 
vent the  Wade  from  cutting  too  far. 

The  pruning  saw  (Fig.  165)  is  useful  for  cutting  off 
large  limbs.  Two  toothed  edges  are  preferable  to  one, 
as  the  second  edge  tends  to  prevent  "pinch- 
ing." It  is  well  to  have  the  teeth  on  one  edge 
point  backward,  as  this  enables  the  saw  to  cut 
either  when  pushed  or  pulled.  Sometimes  the 
blade  is  curved 
like  a  sabre,  with 
the  teeth  on  the 
concave  edge 
pointing  back- 
ward. The  blade 
should  taper  near- 
ly to  a  point,  to 
enable  it  to  enter 
between  crowded 
branches. 

The   pruningl 
shears    (Fig.   166)  FIG.  IBS.          FIG.  169.       FIG.  170. 

FIG.  168.     Lever    shears    (much    reduced). 

may     be     Used     tor        FIG.  169.     Pole    shears.       The    wire    con- 
nects with  a  lever  not  shown  in   the  figure. 
the     Same    purpose        FlG-  17°-     Raspberry    hook. 

as  the  pruning  knife,  but  they  cut  less  smoothly,  and 
less_closejto  the  supporting  member.  They  should  be 
used  with  the  beveled  edge  of  the  blade  in  close  contact 


Pruning.  269 

with  the  supporting  member.  They  are  excellent  for 
cutting  cions  (386),  and  making  cuttings  (358).  The 
form  shown  in  the  figure  is  perhaps  the  best  one  extant. 

The  hedge  shears  (Fig.  167)  are  especially  useful  for 
pruning  hedges. 

The  lever  shears  (Fig.  168)  are  useful  for  cutting 
off  sprouts  about  the  base  of  trees. 

The  pole  shears  (Fig.  169)  are  useful  for  cutting 
back  the  shoots  of  tall  trees,  and  for  removing  sap 
sprouts  (223),  though  for  this  purpose  they  have  the 
fault  of  the  pruning  shears  in  not  cutting  sufficiently 
close  to  the  branch.  They  should  not  be  used  for  shoots 
much  exceeding  one-half  inch  in  diameter. 

The  raspberry  hook  (Fig.  170)  is  used  for  cutting 
off  the  dead  fruiting  canes  of  the  raspberry  and  black- 
berry. The  cutting  part  is  made  of  a  rod  of  good  steel, 
five-sixteenths  inch  in  diameter,  flattened  and  curved  as 
shown,  with  a  moderately  thin  edge  on  the  concave 
side  of  the  curve.  The  handle  should  be  about  three 
feet  long. 


The  following  books  are  recommended  for  reading  in 
connection  with  the  preceding  chapter:  The  Nursery 
Book,  Bailey;  Greenhouse  Construction,  Taft;  Barry's 
Fruit  Garden,  Barry ;  The  Art  of  Grafting,  Baltet ;  The 
Pruning  Book,  Bailey;  How  to  Make  the  Garden  Pay, 
Greiner. 


CHAPTER  V. 
PLANT  BREEDING. 

432.  Plants  Have  Improved  Under  Culture.     From 
our  point  of  view,  our  cultivated  varieties  of  plants  are 
superior  to  their  wild  prototypes.*-  The  strawberries  of 
our   gardens   are   larger,   more   productive   and   firmer 
than  those   of   the   fields;   the   cultivated   lettuces   are 
more  vigorous,  more  tender  arid  milder  in  flavor  than 
wild  lettuces;   and  the  cultivated  cabbages  and  cauli- 
flower are  greatly  superior,  in  the  food  products  they 
furnish,  to  their  progenitor.     The  superior  qualities  of 
long-cultivated   plants,    as    compared    with    their    wild 
parents,    is    conspicuous    whenever    the  wild    form   is 
known. 

433.  Whence   this    Improvement?     It   probably   re- 
sults from  two  causes,     a — In  culture,  the  natural  hin- 
drances  to   development   are   largely   removed.     Culti- 
vated  plants   are   less   crowded  by  too-near  neighbors 
than   wild   plants,    and   they   commonly   receive    more 
abundant  food  and  moisture.     They  are,  therefore,  able 
to  reach  higher  stages  of  development  than  is  possible 
in   nature,   where   plants   are   constantly  restricted   by 
environment. 

b — The  principle  of  selection  has  doubtless  been  more 
or  less  operative  since  the  beginning  of  culture  (19). 
All  of  our  cultivated  plants  must  have  existed  origi- 
nally in  the  wild  state.  The  most  satisfactory  plants 
of  any  desirable  species  have  been  most  carefully 


Plant   Breeding.  271 

guarded,  and  when  the  art  of  propagation  became 
known,  these  plants  were  most  multiplied.  In  each 
successive  generation,  the  most  desirable  individual 
plants  of  each  species  were  protected  and  multiplied, 
or  at  least  were  permitted  to  perpetuate  themselves. 
Since  the  offspring  tends  to  resemble  the  parent  (18), 
the  persistent  propagation  from  the  best  has  resulted 
in  more  or  less  marked  improvement.  Chance  cross- 
ings have0  aided  the  process  (445).  These  facts  fur- 
nish hints  for  the  further  improvement  of  plants. 

434.  The   Variability   of  plants   Renders   their   Im- 
provement Possible.  ~*  In  a  species  of  which  the  indi- 
vidual plants  are  all  practically  alike,  as  in  many  wild 
plants,  we  can  do  little  in  the  way  of  plant  breeding, 
except  to  give  treatment  that  promotes  variability.     In 
a  species  in  which  the  individuals  manifest   different 
qualities,  however,  we  may  hope  to  secure  improvement 
by  using  the  more   desirable   plants   as   parents   from 
which  to  secure  still  further  variability. 

435.  Variations  are  Not  Always  Permanent.     If  we 
find  a  chance  seedling  of  the  wild  blackberry,  for  ex- 
ample,   that    has    remarkably    fine    fruit,    the    plants 
grown  from  seeds  of  this  fruit  are  not  always  equal  in 
quality  to  the  parent.     The  tendency,  in  such  cases,  is 
for  the  seedling  plants  to  revert  or  go  back  to  the  ordi- 
nary type  of  the  species,   and  the  more  marked  the 
variation,  the  stronger  is  the  tendency  to  reversion. 

436.  How    to    Fix    Desirable    Variations.     A    fixed 
variation,  i.   e.,  a  variation  of  which  the  progeny  re- 
sembles  the    parent    in    all    important    characters,    be- 


272  Principles  'of  Plant  Culture. 

comes  a  variety  (21)*  as  this  word  is  used  with  refer- 
ence to  cultivated  plants.  .There  are  two  possible  ways 
of  fixing  a  desirable  variation: 

a — By  propagating  the  plant  by  division  (345).  This 
enables  us  to  maintain  a  given  variation  through  many 
generations  with  comparatively  little  deviation  from 
the  form  with  which  we  started  (341).  Our  varieties 
of  fruits,  potatoes,  geraniums  and  many  flowering  plants, 
and  of  many  of  our  finest  ornamental  trees  and  shrubs 
are  fixed  in  this  manner.  It  is  well  known  that  varie- 
ties propagated  in  this  way  rarely  "come  true"  from 
seed,  i.  e.,  their  seed  does  not  usually  produce  plants  of 
the  same  variety  as  the  parent.  But  it  is  not  practi- 
cable to  propagate  all  plants  by  division. 
'  With  plants  more  conveniently  propagated  from  seed, 
as  the  cereals,  Indian  corn  and  most  garden  vegetables, 
we  may  fix  varieties  to  a  certain  limit. 

b — By  persistent  selection  toward  an  ideal  type.  For 
example,  if  we  discover  a  single  pea  plant  in  a  row  of 
peas  that  produces  earlier  pods  than  any  other  plant 
and  we  desire  to  fix  this  variation,  we  would  save  all 
the  peas  from  this  plant  and  sow  them  the  next  spring. 
Most  of  the  plants  from  this  seed  will  probably  be  later 
than  the  parent,  but  two  or  three  of  them  may  equal 
it  in  earliness.  We  would  save  the  seeds  from  the 
earliest  plant  again,  and  continue  this  selection  through 
several  seasons.  It  would  be  well  to  note  the  incidental 
characters  of  the  earliest  plants,  i.  e.,  whethe-r  the  pods 
are  borne  singly  or  in  pairs,  if  they  are  straight  or 


*  Varieties    that  produce  their  more   important  characters   when 
grown  from   seed,   are   often   called   races. 


Plant   Breeding.  273 

crooked,  and  whether  the  plants  are  tall  or  dwarf.  Hav- 
ing decided  on  the  characters  that  ".seem  to  accompany 
the  extreme  earliness,  we  should  save 'seeds  only  from 
plants  that  show  all  these  characters.  After  following 
this  kind  of  selection  eight  or  ten  years,  we  may  be 
able  to  introduce  a  new  variety  of  pea. 

It  is  impossible  to  so  fix  variations  in  plants  grown 
from  seed  that  they  will  continue  to  come  true  without 
a  certain  amount  of  selection,  hence  varieties  propa- 
gated by  seed  continually  tend  to  "run  out,"  i.  e.,  to 
lose  their  distinctive"  characters.  Seed  growers  find  it 
necessary  to  use  the  utmost  care  in  maintaining  their 
varieties,  and  the  more  distinct  a  variety  propagated 
by  seed,  the  more  difficult  it  is  to  maintain. 

437.  Seed  Selection  is  of  Great  Importance.    From 
what  has  been  said,  it  is  clear  that  the  cultivator  can- 
not  afford  to  be  indifferent  as  to  the  quality  of  the 
seed  he  SOWTS.     It  is  not  enough  that  the  seed  is  fresh 
and  plump ;  it  should  be  of  carefully-bred  varieties.     In 
the  cabbage  and  cauliflower,  success  or  failure  in  the 
crop  will  depend  largely  upon  the  quality  of  seed  sown, 
and  the  same  is  more  or  less  true  in  all  crops  grown 
from  seed. 

438.  We   Can    Induce   Variation,   in  some  cases,   by 
special  treatment  of  the  parent  p]ants,  or  by  the  use  of 
a  particular  selection  of  seed. 

a— By  culture.  It  is  generally  conceded  that  culture 
tends  to  promote  variations  that  would  not  have  ap- 
peared in  the  wild  state,  in  consequence  of  the  changed 
growth  conditions.  In  improving  wild  plants,  there- 
fore, we  probably  have  a  better  chance  of  securing 


274  Principles  of  Plant  Culture. 

variation  by  gathering  seeds  from  such  wild  plants  that 
have  been  placed  under  high  cultivation  than  from 
those  that  have  not  been  submitted  to  culture. 

b — By  growing  seedlings.  In  plants  habitually  pro- 
pagated by  division  (345),  as  the  apple,  potato,  dahlia, 
etc.,  we  secure  variation  by  growing  plants  from  seed. 
The  parent  plant,  not  having  been  fixed  by  long  selec- 
tion, as  is  the  case  with  varieties  grown  from  seed,  is 
in  a  state  of  variation,  and  hence  its  progeny  usually 
varies  widely.  From  these  variable  seedlings,  desirable 
individuals  may  be  selected  for  fixing.  Since  most  of 
our  varieties  that  are  propagated  by  division  are  highly 
developed,  their  seedlings  are  usually,  though  not  nec- 
essarily, inferior  to  the  parents. 

c — By  crossing  varieties  or  species.  This  is  the  most 
important  method  of  plant  improvement.  By  procur- 
ing fecundation  of  the  germ  cell  of  a  plant  of  one  vari- 
ety with  pollen  from  a  plant  of  a  different  variety  or 
species  (149)  through  cross-pollination  (151),  we  ob- 
tain a  variable  progeny  of  which  the  individual  plants 
may  be  expected  to  resemble  both  parents  in  different 
degrees.  For  example,  if  we  secure  fecundation  of  a 
number  of  ovules  of  the  "Worden  grape  with  pollen 
from  the  Delaware  grape,  and  plant  the  seeds  from  the 
fruits  thus  secured,  we  may  expect  that  some  of  the 
seedlings  will  resemble  both  parents  about  equally,  that 
others  will  chiefly  resemble  the  Worden,  but  will  show 
a  few  characteristics  of  the  Delaware,  while  others 
again  will  chiefly  resemble  the  Delaware,  but  will  pos- 
sess a  few  characteristics  of  the  Worden.  It  would  not 
be  surprising  if  we  secure  a  vine  having  the  vigor, 


Plant  Breeding.  275 

productiveness  and  large  fruit  of  the  Worden,  with  the 
color  and  delicious  flavor  of  the  Delaware.  This  we  may 
almost  certainly  acomplish  if  we  continue  our  trials  a 
sufficient  time.  In  other  words,  we  may  often  combine 
the  good  qualities  of  two  varieties  into  a  single  variety 
by  securing  a  number  of  cross-fecundations  between 
the  two  (440),  and  rearing  plants  from  the  seeds  thus 
formed. 

439.  The  Selection  of  Subjects  for  Crossing.  If 
the  object  of  crossing  is  simply  to  secure  variation,  as 
is  sometimes  the  case  with  wild  fruits,  the  parents 
should  differ  from  each  other  as  widely  as  posibble, 
provided  only  that  they  are  capable  of  crossing  freely. 
Crosses  between  allied  species  (hybrids (23)),  when  this 
is  possible,  will  be  more  likely  to  accomplish  the  object 
sought  than  between  plants  of  the  same  species. 

If  the  object  is  the  improvement  of  present  varieties, 
the  parents  should  be  chosen  with  reference  to  the 
qualities  desired  in  the  new  variety.  For  example,  if 
it  is  desired  to  produce  a  hardy,  late-keeping  apple, 
of  first  quality  any  hardy  variety  that  keeps  well,  what- 
ever its  quality,  may  be  crossed  with  any  other  hardy 
apple  of  first  quality,  whether  it  keeps  poorly  or  well, 
though  of  two  apples  of  first  quality,  the  better  keeper 
should  be  chosen. 

The  plant  breeder  should  first  have  a  definite  idea  of 
the  qualities  he  desires  to  secure  in  his  proposed  vari- 
ety, and  should  then  study  with  much  care  the  qualities 
of  the  varieties  that  he  proposes  to  use  as  parents.  The 
two  varieties  that  contain  the  largest  number  of  the 
desired  qualities  should  be  chosen. 


276  Principles  of  Plant  Culture. 

440.  Cross-Fecundation     is     accomplished     through 
cross-pollination  of  the  flowers   (151)  ;  i.  e.,  by  placing 
pollen  from  the  anthers  of  a  flower  of  one  of  the  varie- 
ties we  desire  to  cross  upon  the  stigma  of  the  other 
variety. 

441.  Preparing  the   Flower   for  Crossing.     To   pre- 
vent self-pollination   (151)   in  perfect  flowering  plants 
(153),  we  emasculate  (e-mas'-cu-late)  the  flowers,  i.  e., 
remove  the  anthers  (143)   before  the  pollen  is  mature. 
Prior  to  maturity,   the  anthers 

are  generally  pale  in  color  and 
nearly  smooth  on  the 
surface,  with  no  visible 
pollen,  but  a  little  later, 
the  pollen  in  most 
plants  is  visible  as  a 
bright  yellow  dust  ad- 

FIG.  171.     Case  of  instruments  and 

hering  to  the  anthers.  sacks  for  crossing  plants. 
The  anthers  may  be  picked  off  with  the  forceps,  or 
the  filaments  that  support  them  may  be  clipped  off  with 
the  points  of  the  scissors.  They  must  generally  be  re- 
moved before  the  petals  open  (142).  The  latter  may 
be  gently  opened  with  the  forceps  or  needle,  or  they 
may  be  carefully  removed. 

In  the  flowers  of  certain  plants,  as  the  pea,  wheat  and 
grape,  pollination  takes  place  before  the  blossom  opens, 
hence  in  these  plants  it  is  necessary  to  emasculate  the 
flowers  very  early. 

442.  To    Prevent    Undesired    Pollination,    the    blos- 
som should  be  inclosed  by  tying  over  it  a  sack  of  thin 
cloth  or  paper  at  the  time  of  removing  the   anthers. 


Plant   Breeding. 


277 


The  sack  will  of  course  have  to  be  removed  for  polli- 
nation, after  which  it  should  be  promptly  replaced. 

Pollination  should  be  performed  twenty-four  to  forty- 
eight  hours  after  emasculation  (441),  the  period  de- 
pending upon  the  plant 
and  the  stage  of  develop- 
ment of  the  flower  at  the 
time  of  the  latter  opera- 
tion (150).  Applying 
the  pollen  on  two  consec- 
utive days  tends  to  in- 
sure success. 

The  pollen  is  applied 
by  placing  an  anther 
(143)  containg  mature 
pollen  in  direct  contact 

FIG.    172.     Emasculated   flower    in-  with     the     Stigma      (144), 

or   by  removing  some  of 

the  pollen  upon  the  back  of  the  point  of  a  penknife  or 
by  means  of  a  camel's-hair  brush,  and  carefully  apply- 
ing it  to  the  stigma.  A  pin,  of  which  the  head  has 
been  flattened  by  hammering,  inserted  in  the  end  of  a 
stick,  forms  a  convenient  tool  for  this  work.  A  slen- 
der stick  of  sealing  wax  drawn  to  a  blunt  point  may  be 
used  in  pollination  by  rubbing  it  on  the  sleeve  to 
electrify  it. 

The  best  time  for  pollination  in  the  open  air,  is  often 
in  the  early  morning,  since  the  atmosphere  is  then 
usually  still,  and  contains  little  pollen  from  other  flow- 
ers, which,  if  freely  present  in  the  air  may  vitiate  the 
results  of  the  pollination. 


278  Principles  of  Plant  Culture. 

443.  The  After-Care  of  Crosses.     After  the  last  pol- 
lination,  the   blossom   should    again  be   inclosed  until 
fecundation  is  effected,  which  is  indicated  by  a  rapid 
enlargement  of  the  ovary.     The  paper  sack  may  then 
be  replaced  by  one  of  mosquito  netting.     This  should 
be  securely,  but  not  too  tightly,  tied  about  the  stem  of 
the  pollinated  flower,  to  protect  the  inclosed  fruit  or 
seed-vessel   from  injury  during  growth  and  maturity, 
as  well  as  to  render  it  conspicuous.     A  label  should  be 
placed  within  the  sack,  or  tied  on  with  it,  giving  the 
name  of  the  variety  whence  the  pollen  was  secured.     It 
is  also   desirable  to  record  all  the  operations  and  ob- 
servations relative  to  the  crossing. 

444.  The  Selection  of  Crossed  Seedlings  is  a  most 
important    operation    in    producing    new    varieties    by 
crossing.     If  none  of  the  seedlings  of  the  first  genera- 
tion exhibit  the  desired  qualities,  those  of  a  succeeding 
generation  may  exhibit  them.     The  plants  nearest  the 
ideal  should  be  selected,  and  all  the  seeds  from  these 
preserved    for     planting.    When    the    ideal    plant   is 
found,  it  may  be  readily  fixed  by  means  of  cuttings  or 
grafts  in  plants  generally  propagated  in  this  way.     In 
those  propagated  by  seed,  several  generations  of  cul- 
ture and  selection  may  be  necessary  before  the  progeny 
will  uniformly  resemble  the  parent. 

The  variations  in  the  seedlings  from  two  crossed 
varieties,  and  the  kind  of  selection  needed  to  fix  the  de- 
sired variations,  are  illustrated  by  the  following  dia- 
gram (Fig.  173).  Let  a  represent  the  seeds  from  two 
crossed  flowers  A  and  B.  The  plants  from  these  seeds 
will  probably  be  quite  variable,  as  is  indicated  by  the 


Plant  Breeding.  279 

divergent  lines.  Let  us  suppose  the  variation  marked  i 
to  be  the  nearest  the  ideal  form.  The  plants  grown 
from  i  will  again  be  quite  variable  in  the  second  gen- 


FIG.  173.     Diagram    illustrating    the    selection    of   seedlings    from 
a   cross. 

eration  I,  but  probably  less  so  than  in  the  first  genera- 
tion. No  plants  of  the  second  generation  may  be  nearer 
the  ideal  type  than  those  of  the  first  generation,  but 
we  select  the  plant  nearest  to  our  ideal,  and  plant  the 
seeds  from  this.  Each  succeeding  generation  may  be 
expected  to  produce  less  of  variability  than  the  one 
before  it.  By  and  by,  we  may  hope  to  secure  a  form 
that  approaches  our  ideal  and  comes  tolerably  true 
from  seed. 

445.  Planting  with  Reference  to  Chance  Crossings. 
Many    valuable    varieties    have    unquestionably  arisen 
from  accidental  crosses  between  plants  of  different  va- 
rieties that  chanced  to  be  growing  in  proximity.  Profit- 
ing by  this  hint,  varieties  are  sometimes  planted  near  to- 
gether to  favor  self-crossing,  a  practice  to  be  encouraged. 

446.  Those   Who   Improve   Plants  are  True   Bene- 
factors.    He  who  produces  fruits  or  flowers  for  others 
works  a  transient  good.     But  he  who  produces  a  variety 
of  fruit  or  flower  that  is  superior  to  any  now  known 
confers  upon  his   race   a  permanent   good.     Until  the 
introduction  of  the  Wilson  strawberry,  the  markets  of 
our  country  were  not  supplied  with  this  delicious  and 


280  Principles  of  Plant  Culture. 

wholesome  fruit,  because  no  known  variety  was  suffi- 
ciently productive  to  be  generally  profitable,  or  suffi- 
ciently firm  to  endure  long  carriage.  What  a  blessing 
was  conferred  upon  us  by  a  Mr.  James  Wilson,  of  Al- 
bany, N.  Y. !  There  are  wild  fruits  in  our  copses  to-day 
that  are  doubtless  worthy  of  improvement,  and  in  most 
of  our  fruits  now  under  culture  the  development  of 
superior  varieties  would  greatly  enhance  their  value. 
"The  harvest  truly  is  great,  but  the  laborers  are  few." 


The  following  books  are  recommended  for  reading  in 
connection  with  the  preceding  chapter:  Plant  Breed- 
ing, Bailey;  Variations  of  Animals  and  Plants  Under 
Domestication,  Darwin;  Propagation  and^  Improve- 
ment of  Cultivated  Plants,  Burbridge ;  Origin  of  Culti  - 
vated  Plants,  De  Candolle. 


APPENDIX 


A  SYLLABUS  OF  LABORATORY  WORK. 

The  laboratory  exercises  here  outlined  have  been 
used  by  the  author  in  his  instructional  work. 

Each  student  performs  the  exercises,  so  far  as  possi- 
ble, and  the  apparatus  needed  is  provided.  The  stu- 
dent should  be  required  to  write  a  description  of  the 
work  performed,  stating  results  in  every  case,  supple- 
menting his  notes  by  drawings  in  special  cases. 

It  has  not  been  found  practicable  to  make  the  lecture 
rocm  and  laboratory  work  fully  correspond  as  to  time, 
but  the  effort  has  been  made  to  do  this  as  far  as  possoble. 

A  greenhouse  is  very  desirable  for  this  kind  of  in- 
struction, and  if  the  instruction  is  given  in  winter,  a 
"garden  house,"  i.  e.,  a  glass  house  inclosing  an  unob- 
structed area  of  garden  soil  is  scarcely  less  important. 
But  in  the  absence  of  these  conveniences,  a  few  win- 
dow boxes  will  furnish  a  tolerable  substitute. 

When  the  exercises  are  carried  out  during  winter, 
considerable  foresight  is  essential  to  have  the  needed 
materials  in  condition  for  use  at  the  proper  time. 

To  stimulate  observation (1).*  A  few  object  lessons 
are  given  to  encourage  observation  and  correct  reason- 
ing. A  twig,  an  ear  of  corn  or  a  potato  tuber  is  given 
to  each  student  and  all  are  encouraged  to  vie  with  each 
other  in  discovering  new  points,  and  in  discussing  the 
reasons  therefor.  This  lesson  is  frequently  repeated 
during  the  term. 

*  The    numbers    in   parenthesis    refer    to    the    paragraphs    in    the 
book. 
19 


Principles  of  Plant  Culture. 

Cell  structure  (12).  The  students  examine  the  pulp 
of  a  mealy  apple  and  of  a  potato,  and  cross-sections  of 
a  young  bean  plant,  with  simple  lenses  of  rather  high 
magnifying  power.  If  a  compound  microscope  is  avail- 
able, many  mounted  objects  illustrating  the  cell  struc- 
ture of  plants  may  also  be  shown. 

Absorption  of  water  by  seeds  (26.) 
For  the  exercise  suggested  by  paragraphs 
26  and  27,  a  means  of  weighing  and  of 
measuring  the  volume  of  large  seeds,  as 
beans,  with  some  degree  of  accuracy  is 
needed.  The  device  shown  in  Fig.  174 
answers  this  purpose,  and  one  can  be 
provided  for  each  pair  of  students  at  a 
moderate  cost.  It  consists  of  a  graduated 
glass  cylinder  of  200  cubic  centimeters 
capacity  and  a  test  tube  about  6  inches 
long.  For  determining  the  volume,  the 
cylinder  is  partly  filled  with  water  and 
the  height  to  which  the  water  rises  is 
loted.  The  seeds  are  then  dropped  in 
and  the  glass  is  -shaken  a  little  to  re- 
move the  air  bubbles.  The  height  of  the 
water  is  again  noted,  when  the  difference 
in  the  two  readings  indicates  the  volume 
of  the  seeds  in  cubic  centimeters.  For 
weighing  the  empty  test  tube  is  placed  in 
the  cylinder  in  the  position  shown  (Fig. 
174).  The  height  to  which  the  water 
rises  is  then  noted,  after  which  the  seeds 


fe 

determining  the  are  dropped  into  the  test  tube,  and  the 

volume  of  seeds.     top   Qf  the   cylinder   ig  jarred   sightly  by 

tapping  it  with  a  pencil.  The  height  of  the  water  is 
again  noted,  when  the  difference  in  the  readings  indi- 
cates the  weight  of  the  seeds  in  grammes. 

The  test  tube  should  float  in  the  center  of  the  cylin- 
der, as  shown,  and  the  readings  should  be  taken  with 
the  eye  on  a  level  with  the  surface  of  the  water. 

Each  student  (or  pair  of  students)  is  provided  with 
the  apparatus  shown  in  Fig.  174,  and  with  two  bottles 


Appendix— Syllabus  of  Laboratory  Work.       283 

of  at  least  100  cc.  capacity,  with  corks.  Each  bottle 
should  have  a  strip  of  white  paper  pasted  vertically 
upon  it  to  receive  the  name  of  the 'student  and  other 
data. 

Each  student  weighs  or  measures  the  volume  of  50 
fresh  seeds  of  the  bean,  pea  or  Indian  corn  in  the  man- 
ner described  above.  Having  noted  the  weight  or  vol- 
ume in  his  note  book,  he  pours  the  seeds,  with  the 
water,  into  one  of  his  bottles,  corks  the  latter  and  writes 
his  name,  with  the  date,  on  the  paper  pasted  on  its  side. 
He  then  repeats  the  process  with  seeds  cf  the  honey 
locust,  yellow  wrood  or  some  other  seed  that  does  not 
readily  absorb  cool  water,  and  after  recording  the  data 
in  his  notebook,  places  the  bottles  in  a  warm  place  until 
the  following  day,  wnen  he  again  determines  the  weight 
or  volume  of  the  two  kinds  of  seeds.  The  seeds  placed  in 
the  first  bottle  will  usually  be  found  to  have  nearly  cr 
quite  doubled  in  size,  while  those  in  the  second  bottle 
have  scarcely  swollen  at  all. 

Next,  show  the  class  a  sample  of  the  second  lot  of 
seeds  that  have  fully  swollen  from  soaking  in  hot  water. 
Impress  upcn  their  minds  the  fact  that  while  most 
seeds  readily  absorb  moisture  at  ordinary  temperatures, 
a  few  kinds  do  not,  and  seeds  of  the  latter  class  need 
to  be  soaked  cautiously,  before  planting,  in  hot  water 
(27  d.) 

The  rate  at  which  seeds  absorb  water  depends 

a — Upon  the  water  content  of  the  medium  (27). 
Weigh  3  samples  of  navy  beans.  Place  one  sample  in 
water,  a  second  in  very  damp  earth  and  the  third  in 
slightly  damp  earth.  Weigh  again  the  next  day  and 
compute  the  water  absorbed  by  the  three  lots. 

b— Upon  the  point  of  contact.  Weigh  2  samp]es  of 
navy  beans,  placing  one  sample  in  moist  soil  without 
compacting,  and  the  second  in  the  same  kind  of  soil  well 
compacted  about  the  seeds.  Determine  the  water  ab- 
sorbed by  the  two  samples  the  next  day. 

c — Upon  temperature.  Repeat  the  above  with  2  sam- 
ples of  navy  beans,  placing  one  lot  in  a  temperature  of 
80°  to  90°  F.,  and  the  other  in  40°  to  50°  F. 


2S4  Principles  of  Plant  Culture. 

Other  means  of  using  the  apparatus  shown  in  Fig. 
174  will  occur  to  the  thoughtful  teacher.  It  may  be 
used  for  determining  specific  gravities  by  dividing  the 
weight  by  the  volume. 

Germination  (28).  Give  an  exercise  in  testing  seeds 
with  the  apparatus  shown  in  Fig.  6. 

Moisture  essential  to  germination  (29).  Soak  one  lot 
of  navy  beans  in  water  until  they  are  fully  swollen, 
and  another  lot  until  they  are  about  half  swoTen.  Wipe 
the  beans  as  dry  as  possible,  put  each  lot  into  a  bottle, 
cork  the  bottles,  and  set  them  in  a  warm  room.  The 
fully-swollen  beans  will  usually  germinate  promptly, 
while  the  others  wi?l  not. 

Oxygen  essential  to  germination  (31).  Perform  the 
saucer  experiment  as  described. 

Also  place  seeds  of  rice  in  two  bottles,  and  add  to 
each,  water  that  has  been  boiled  20  minutes;  cover  the 
water  in  one  bcttle  with  a  little  olive-  or  cotton-seed  oil. 
It  is  important  to  soak  the  seeds  a  short  time  in  boiled 
water  before  putting  them  into  the  bottles  to  remove 
the  air  in  contact  with  their  seed-cases. 

Germination  hastened  by  soaking  seeds  (35).  Soak 
seeds  of  Indian  corn  two  or  three  hours  in  warm  water, 
and  let  each  student  place  in  a  seed  tester  a  sample  of 
the  soaked  seeds,  with  one  or  two  other  seeds  of  the 
same  kind  that  have  not  been  soaked. 

Germination  hastened  by  mutilating  the  seed-case 
(36).  This  may  be  illustrated  with  seeds  of  the  navy 
bean,  in  the  seed-tester. 

The  plantlet  (40).  Place  seeds  of  radish,  onions,  etc.. 
loosely  on  the  surface  of  a  saucer  filled  writh  fine  moist 
loam ;  keep  the  surface  moist  and  note  the  repeated  at- 
tempts of  the  hypccotyl  to  enter  the  soil. 

Seeds  of  the  pumpkin  family  should  be  planted  flat- 
wise (42).  Plant  seeds  of  the  pumpkin  or  squash,  -a 
the  three  positions  indicated,  in  large  greenhouse  sau- 
cers. Cover  each  saucer  with  a  pane  of  glass  and 
place  all  in  a  warm  room  until  the  plantlets  appear, 
after  which  note  the  number  of  each  lot  of  seeds  of 
which  the  seed-case  appears  above  the  surface. 


Appendix— Syllabus  of  Laboratory  Work.       285 

Development  of  plantlets  (44-46).  Devote  several  ex- 
ercises to  a  study  of  the  development  of  plantlets  of 
the  bean,  pea,  wheat,  Indian  corn,  pumpkin,  etc.  To 
furnish  the  plantlets,  seeds  of  the  different  sorts  should 
be  planted  on  several  successive  days,  beginning  at 
least  10  days  in  advance. 

Not  all  seeds  should  be  deeply  planted  (47).  Plant 
seeds  of  the  bean,  pea,  Indian  corn  and  wheat  in  6-inch 
flower  pots,  at  three  different  depths,  viz.,  i/2  inch,  3 
inches  and  6  inches  from  the  bottom;  place  the  pots  in 
a  warm  place  for  3  weeks,  after  which  carefully  re- 
move the  soil,  noting  the  germination  of  the  seeds  in 
the  different  layers. 

Vigor  of  plantlet  proportionate  to  size  of  seed  (48). 
Plant  large  and  small  specimens  of  navy  beans  by  them- 
selves, in  greenhouse  saucers,  and  permit  them  to  ger- 
minate. The  smaller  seeds  usually  germinate  earlier 
than  the  larger,  but  they  produce  more  slender  plant- 
lets,  which  soon  fall  behind  the  others  in  development. 

Plantlet  visible  in  the  seed  (53).  Boil  samples  of 
various  kinds  of  seeds  until  they  are  fully  swollen, 
after  which  require  the  students  to  dissect  them  and  to 
seek  out  the  plantlets.  Lenses,  needles  and  forceps  are 
very  useful  in  this  work. 

The  cotyledons  a  storehouse  for  food  (59).  Remove 
the  cotyledons  of  some  bean  plantlets  growing  in  a 
flower  pot  or  saucer,  leaving  those  of  other  plantlets 
intact.  After  a  week  note  the  result  in  the  checked 
growth  of  the  mutilated  plants. 

Vascular  bundles  (67).  Study  these  as  shown  in  the 
stalk  of  Indian  corn,  in  the  leaf  stems  of  various  plants 
and  in  the  leaf  scars  on  the  stems  of  plants. 

Cambium  layer  (68).  Locate  this  in  sections  of 
various  dicotyledonous  stems,  including  the  potato  tu- 
ber; also  note  the  absence  of  the  cambium  layer  in 
monocotyledonous  stems. 

Root-hairs  (100).  Study  these  as  illustrated  when 
seeds  germinate  in  the  seed  tester.  Germinated  radish- 
seeds,  left  in  the  seed  tester  two  or  three  days,  usually 
develop  root-hairs  in  great  abundance.  Also  search  out 


286  Principles  of  Plant  Culture. 

the  root-hairs  in  potted  plants.  Emphasize  the  differ- 
ence between  root  hairs  and  root  branches. 

Effects  of  transplanting  on  root  branching  (104). 
Study  young  plants  of  lettuce,  tomato,  cabbage,  etc , 
that  have  been  pricked  off,  and  compare  their  roots 
with  those  of  others  that  have  not  been  pricked  off. 

Relation  of  roots  to  food  supply  (111).  Plant  seeds 
of  the  radish  in  saucers  containing  clean  sand  and  pot- 
ting soil  respectively,  and  when  the  seedlings  have  at- 
tained some  size,  wash  out  and  examine  the  roots  in 
the  two  soils. 

Root  tubercles  (112).  Study  the  roots  of  young 
clover  plants  of  various  ages,  and  note  how  early  in  th ; 
development  of  the  plant  the  tubercles  are  discernible. 

Underground  stems  (114).  Study  the  development 
of  the  potato  plant  from  growing  specimens,  noting  the 
points  at  which  the  tuber-bearing  stems  originate,  and 
the  marked  difference  between  these  and  the  roots. 

Nodes  and  internodes  (115).  Observe  the  nodes  in 
the  stems  of  many  plants,  noting  the  relation  of  the 
diameter  of  the  young  stem  to  the  length  of  the  inter- 
nodes;  also  note  the  undeveloped  internodes  near  the 
terminus  of  the  stem. 

Buds  (127).  Study  specimens  of  leaf -buds  from 
many  plants,  noting  their  structure,  position,  etc. 

Flower-buds  (132).  Study  the  form  and  location  of 
the  flower-buds  in  many  plants,  particularly  in  fruit 
trees. 

Parts  of  the  flower  (140).  Study  the  parts  of  the 
flower,  explaining  the  function  of  each  part. 

Perfect  and  imperfect  flowers  (153).  Study  these 
as  produced  by  several  different  plants,  particularly  of 
the  strawberry. 

Degree  of  maturity  necessary  to  germination  (162). 
Test  seeds  of  Indian  corn,  pea,  tomato,  etc.,  that  were 
gathered  at  varying  stages  of  maturity. 

Seed  vitality  limited  by  age  (164).  Test  seeds  of 
lettuce,  parsnip,  onion,  etc.,  1  year,  2  years  and  5  years 
old,  respectively. 


Appendix — Syllabus  of  Laboratory  Work.       287 

Stratification  of  seeds  (169).  Perform  the  process, 
as  described,  in  boxes  or  large  flower  pots. 

Sun-scald  (185).  Require  each  student  to  make  a 
lath  tree  protector  (Fig.  59). 

Winter  protection  of  plants  (201).  Protect  half- 
hardy  shrubs  by  wrapping  them  with  straw  or  covering 
them  with  earth. 

Foretelling  frost    (206).     Devote  an  exercise  to  the 
use  of  the  psychrometer  and  the  computation  of 
dew  point. 

Plant  protectors  (278).  Require  each  student  to 
make  at  least  one  plant  protector,  as  shown  in  Fig.  67, 
patterns  for  which  are  to  be  furnished. 

Kerosene  Emulsion  (294).  Let  each  student  make  a 
given  quantity  of  the  kerosene  emulsion  after  one  of 
the  formulas  given. 

Spraying  pumps  (304).  Give  at  least  one  exercise 
to  the  construction  and  use  of  spraying  pumps  and 
nozzles. 

Prevention  of  grain  smuts  (325).  Require  the  stu- 
dents to  treat  a  quantity  of  oats  with  formalin  as  de- 
scribed. 

Bordeaux  Mixture  (329).  Require  each  student  to 
make  a  stated  quantity  of  the  Bordeaux  mixture  after 
the  formula  given. 

Propagation  by  seeds  (344).  Instruct  the  students 
in  the  use  of  the  hand  seed-drill  and  broadcast  sower. 
Let  them  ascertain  how  much  clover  seed  the  broadcast 
machine  is  sowing  per  acre,  by  laying  on  the  ground  or 
flcor  several  sheets  of  paper,  exactly  one  foot  square, 
painted  with  glycerine  to  catch  the  falling  seeds.  Hav- 
ing learned  the  average  number  of  seeds  deposited  per 
square  foot  with  a  given  rate  of  motion  of  the  machine, 
let  the  students  compute  the  number  of  seeds  sown  per 
acre,  and  reduce  this  to  ounces.  The  number  of  clover 
seeds  in  an  ounce  may  be  ascertained  by  dividing  an 
ounce  of  seed  among  the  students  for  counting. 

Propagation  by  layers  (349).  Instruct  the  students 
in  layering  canes  of  the  grape,  and  in  mound-layering 
the  stems  of  the  gooseberry. 


288  Principles  of  Plant  Culture. 

The  bulb  (352).  Dissect  bulbs  of  the  onion,  tulip, 
lily,  etc.,  ascertaining  their  structure  and  finding  the 
embryo  flowers. 

The  cold-frame  (364).  Require  the  students  to  make 
a  drawing  and  write  a  description  of  a  cold-frame,  from 
a  model  furnished  them. 

The  liotbed  (365).  Let  the  students  assist  in  making 
a  hotbed  after  the  plan  described.  Also  let  them  note 
the  temperature  of  the  soil  within  the  frame  on  sev- 
eral successive  days  after  the  bed  is  finished,  and  give 
them  instruction  in  ventilating  the  hotbed. 

The  propagating  bed  (368).  Require  the  students  to 
make  a  propagating  bed  in  the  greenhouse,  after  the 
plan  described. 

Stem  cuttings  (373-375).  Let  the  students  make 
cuttings  from  the  stems  of  the  grape,  currant,  etc., 
and  plant  them,  both  in  the  propagating  bed  and  in 
the  garden. 

Root-cuttings  (376).  Give  a  lesson  in  making  root- 
cuttings  of  the  raspberry  or  blackberry,  in  packing  the 
same  for  winter  storage,  and  in  planting  them  in  the 
propagating  bed  and  in  the  garden. 

Green  cuttings  (380-381).  Give  a  lesson  in  making 
and  planting  cuttings  of  coleus,  geranium,  rose,  etc., 
followed  by  instructions  in  the  care  of  green  cuttings 
in  the  propagating  bed. 

Leaf  cuttings  (382).  Give  a  lesson  in  making  and 
planting  leaf  cuttings  of  the  begonia. 

Grafting  wax,  etc.  (387-389).  Give  a  lesson  in  mak- 
ing grafting  wax,  grafting  cord  and  -grafting  paper, 
as  described. 

Whip-grafting  (390-391).  Give  several  lessons  in 
whip-grafting  including  grafting  both  of  the  stem  and 
of  the  root. 

Cleft  grafting  (392).  Give  one  or  two  lessons  in 
cleft  grafting. 

Side  grafting  (393).  Give  a  lesson  in  side  grafting, 
as  described. 

Budding  (394).  Give  one  or  more  lessons  in  bud- 
ding, as  described.  The  bark  on  the  stocks  may  be 


Appendix — Syllabus  of  Laboratory  Work.       289 

made  to  peel  by  boiling,  and  trimmed  bud  sticks  may 
be  preserved  for  winter  use,  in  dilute  alcohol. 

Approach  grafting  (399).  Give  one  exercise  in  ap- 
proach grafting  as  described. 

Packing  plants  for  transportation  (405).  Devote  one 
exercise  to  packing  strawberry,  cabbage  or  some  other 
herbaceous  plants,  as  described. 

Heeling-in,  Replanting  (408-410).  Give  one  or  more 
lessons  in  heeling-in  and  planting  trees,  as  described ; 
also  at  least  one  lesson  in  planting  root  grafts,  cuttings 
and  herbaceous  plants  as  shown  in  Figs.  143-144;  and 
a  lesson  in  planting  strawberry  plants. 

Potting  and  shifting  (412).  Give  two  or  more  les- 
sons in  potting  and  shifting  as  Ishown  in  Figs.  145-148. 

Pruning  (427  etc.).  Give  one  or  more  lessons  in 
pruning  by  the  methods  described. 

Cross  pollination  (441).  Give  one  or  more  lessons  in 
cross  pollination,  as  described. 


INDEX 


The  Numbers  refer  to  Pages 


Accumulation  of  reserve  food 
how  to  promote,  93. 

Acid   phosphate,    157. 

Active   state   of  protoplasm,    15. 

Adventitious   buds,    87. 

Aeration  of  soil  promoted  by 
drainage,  70. 

Air-dry   denned,    15. 

Air,    roots    require,    66,    67. 

Ammoniacal  solution  of  copper 
carbonate,  184. 

Ammonium    sulfate,    156. 

Animal   parasites,    160. 

Animals,    domestic,    defined,    11. 

Annular    budding,    232. 

Anther,    97. 

Apparatus  for  applying  insect- 
icides, 171. 

Appendix,    281. 

Apple,  blight  of,  180,  266;  mag- 
got, 176;  scab,  184. 

Approach    grafting,    234. 

Army    worm,    171. 

Arsenate   of  lead,   164. 

Arsenic  compounds,  164;  are 
deadly  poisons,  165. 

Arsenic,    white.    164. 

Arsenite  of  copper,  164;  of 
lime,  158. 

Art  and  science  defined,  9;  how 
best  learned,  10. 

Assimilation    defined,     43. 

Baldridge    transplanter,    247. 

Books  recommended  for  col- 
lateral reading,  117,  188,  269, 
280. 

Bark    bursting,    125. 

Bark,  epidermis     replaced  by,  49. 

Bemis    transplanter.    247. 


Birds,    damage    from,    160,    161. 

Black-heart,    124. 

Black  knot  of   plum,    180,    266. 

Black    rot   of  grape,    184. 

Blanching    of    vegetables,    149. 

Blight  of  apple  and  pear,  180, 
266. 

Bloom   defined,    49. 

Board  screen  for  shading  young 
plants,  146. 

Bordeaux  mixture,  183;  dis- 
eases prevented  by,  184. 

Borers  in  trunks  of  trees,  163, 
175. 

Branches  development  of,  from 
lateral  leaf -buds,  87;  of  trees, 
to  prevent  splitting  down  in 
pruning,  262. 

Branching  stimulated  by 
pinching,  82. 

Branching  of  roots,  condi- 
tions affecting,  74;  how  stim- 
ulated, 75. 

Breeding   defined,    17. 

Brittleness    of    plant    tissues,  60. 

Broom  rape  of  hemp  and  to- 
bacco, 178. 

Brush  screen  for  shading 
plants,  146. 

Bud,    219,    230. 

Budding,  221,  231;  annular,  231; 
ring  231;  shield,  231;  success 
is  dependent  on,  231;  T,  231. 

Budding  knife,   233. 

Buds,    86;    adventitious,    87. 

Buhach,    166. 

Bulb,   197. 

Bulbels,     198. 

Bulblets,     198. 

Bundling  trees  for  transporta- 
tion, 240. 


292 


Index. 


Cabbage  caterpillar,  166;  mag- 
got, 174;  club-root  of,  182. 

Calcium,  part  played  by  in 
plant,  45. 

Callus    how  formed,    56. 

Calyx,    96. 

Cambium  layer,  53;  from  dif- 
ferent plants  may  unite,  54. 

Carbon,  proportion  of  in  vege- 
table material,  44;  sources  of, 
in  plants,  43. 

Caulicle,    33. 

Cauliflower  heads  to  be  shaded 
from  sunlight,  146. 

Caustics,  destroying  insects  by, 
163. 

Cell    division,    15. 

Cells,  guard,  50;  palisade,  49; 
some  properties  of,  14. 

Cellular  structure  of  living  be- 
ings. 13. 

Chili    saltpeter,    156. 

Chinch    bug,    170. 

Chlorid    of    potash,    157. 

Chlorophyll  defined,  41;  forms 
only  in  light,  42;  iron  essen- 
tial to  formation  of,  45;  no 
food  formed  without,  42. 

Chlorophyll    bodies,    42. 

Cion,    219,    221. 

Cion  grafting.   221. 

Classification  defined,  18;  il- 
lustrated, 19. 

Cleft   grafting,    226. 

Close-pollination,    102. 

Clouds  tend  to  avert  frost 
134. 

Clover,  dodder  of,  179;  tuber- 
cles on  roots  of,  79. 

Club-root   of   cabbage,    182. 

Codling    moth,    176. 

Cold  air  drainage,   134. 

Cold,  excessive,  how  affecting 
the  plant,  121. 

Cold-frarre.     203. 

Composite    flowers,    98. 

Conditions  affecting  power  cf 
plants  to  endure  cold,  122. 

Cooling  the  plant,  immediate 
effect  of,  121. 


Copper  carbonate,  ammoniacal 
solution  of,  184. 

Corm,    198. 

Corn,  detasseling,  263;  smut, 
180. 

Corolla,    96. 

Cotyledons    defined,    35. 

Covering  of  seeds  in  planting, 
why  important,  33. 

Cracks  in  fruits  and  vegeta- 
bles due  to  excessive  moist- 
ure, 140. 

Crop,  affected  by  age  of  seed. 
110;  a  growing,  tends  to  con- 
serve fertility,  159;  removal 
of,  tends  to  reduce  plant  food 
in  the  soil,  153;  rotation  of 
economizes  plant  food,  158. 

Crops,  trees  detrimental  to 
neighboring,  59. 

Crossed  seedlings,  selection  of, 
278. 

Crosses,  after  care  of,  278;  and 
hybrids  defined,  20;  varia- 
bility of,  21. 

Cross  fecundation,  how  accom- 
plished, 276. 

Crossing,  selection  of  subjects 
for,  275;  variation  produced 
by,  274. 

Crossings,  planting  with  refer- 
ence to  chance  279. 

Cross-pollination,  102;  advan- 
tage of,  to  plants.  102. 

Cucumber  beetle,  16?;  screen- 
covered  frame  for  hills  of,  162. 

Cucurbitae,  provision  in,  to  aid 
plantlet  to  emerge  from  seed- 
case,  33,  34. 

Cultivation  tends  to  prevent 
drought,  143. 

Culture,  aim  tf.  11;  deals  with 
life,  12;  defined,  10;  plants 
have  improved  under,  270; 
variation  produced  by,  273. 

Curculio    176. 

Currant   worm,    166. 

Current,  evaporation  of.  60;  of 
prepared  food,  62. 

Cuticle    defined,    49. 


Index. 


293 


Cutting  defined,  200;  essential 
characters  of  a,  201. 

Cuttings,  conditions  favoring 
growth  of,  201;  from  active 
plants,  214;  from  dormant 
plants,  209;  from  dormant 
stems,  211;  of  woody  plants, 
preferably  made  in  autumn, 
115;  parts  of  plants  to  be 
used  for,  200;  planting  in  au- 
tumn, 211;  storage  of  210; 
tool  for  planting,  246. 

Cuttings,  green,  214;  especial 
care  necessary  in  propagat- 
ing plants  from,  215;  how 
made  from  herbaceous  plants, 
217;  how  made  from  woody 
plants,  217;  to  be  potted  as 
soon  as  roots  are  formed,  216. 

Cuttings,  leaf,  propagation  by, 
218. 

Cuttings,    mallet,    212. 

Cuttings,  root,  propagation  by, 
213. 

Cuttings,  stem,  211;  to  make 
and  plant,  212. 

Cutworms,    162. 

Dalmatian  insect   powder,    166. 

Damage  from  cold  prevented  by 
protecting  with  non-conduct- 
ing material,  128. 

Damping    off,    216. 

Darkening  of   wood,    124. 

Deflowering   defined,    253. 

Defruiting    defined,    253. 

Density,    pruning   for,    259. 

Depth    of    roots    in    soil,    7,5. 

Destruction  of  terminal  buds 
by  cold,  124.  - 

De-tasseling,    253,    263. 

Devices    for    transplanting,    245. 

Dew  point,  how  to  compute  the 
132;  table  for  computing,  133. 

Dibber,    246. 

Dicotyledons     defined,     36. 

Diffusion,    law    of,    47. 

Dioecious   flowers,   102. 

Disbudding  defined,  253;  trees, 
259. 


Disease    defined,    13. 

Distal    defined,    80. 

Dodder  of  clover  and    flax,    179. 

Domestic  plants  and  animals 
defined,  11. 

Dormant  state  of  protoplasm, 
15. 

Drainage  promotes  soil  aera- 
tion, 70;  required  by  potted 
plants.  70. 

Dressing    defined,     253. 

Drought  causes  toughness  of 
plant  tissue,  143;  cultivation 
a  preventive  of,  143;  mulch- 
ing a  preventive  of,  144;  tends 
to  hasten  maturity,  142. 

Drying  kills  plant  tissues,  144. 

Duration  of  germinating  power, 
108;  of  seed  vitality,  condi- 
tions affecting,  109. 

Electric  light,  use  of,  in  glass 
houses,  149. 

Elements  esential  in  plant 
food,  44;  part  played  by  dif- 
ferent, 44. 

Emasculation    of    flowers,    276. 

Embryo   defined,   40. 

Endosperm    defined.    40. 

Environment  defined,  10;  fac- 
tors of,  118. 

Epidermis  defined,  48;  replaced 
by  bark  in  older  stems,  49. 

Evaporation    current,    60. 

Evergreen  trees  destroyed  by 
untimely  warm  weather  in 
spring,  119. 

Evolution,    theory    of,    21. 

Factors    of    environment,    118. 
Families,    how    formed,    18. 
Farm  manure,  158. 
Fecundation,     100;     cross,     how 

accomplished     276. 
Feebleness    defined,    12. 
Ferns,   how  grown   from   spores, 

39. 

Fertilization,     100. 
Fertilizer  requirements    of  crops, 

158. 


294 


Index. 


Filament,    97. 

Fir    tree   oil,    170. 

Fibro-vascular   bundles,    51. 

Fixing   desirable    variations,  271. 

Flax,    dodder   of,    179. 

Flea   beetles,    168. 

Flower,  95;  certain  parts  of, 
often  wanting,  98;  parts  of 
the,  95;  parts  of.  vary  in 
form  in  different  species,  98. 

Flower-buds,  88;  conditions  af- 
fecting formation  of,  91;  de- 
stroyed by  cold,  126;  how  dis- 
tinguished from  leaf-buds, 
88;  ringing  often  causes  for- 
mation of,  94,  265. 

Flowering  and  fruiting,  root 
pruning  to  promote,  264. 

Flowering,    glumes,   100. 

Flowering,  pinching  to  pro- 
mote. 263. 

Flowers  composite,  98;  espe- 
cially sensitive  to  cold,  127; 
of  the  grass  family,  99;  tend 
to  exhaust  the  plant,  95. 

Flowers  and  fruit,  obstructing 
growth  current  to  promote, 
265;  pruning  for,  263. 

Flow    of    sap    in    spring,    61. 

Food,  current  of  prepared,  62; 
elements  of,  most  likely  to 
be  deficient  in  the  soil,  45; 
insufficient  dwarfs  the  plant, 
153;  materials  of,  how  dis- 
tributd  through  plant,  47;  re- 
serve, 15;  storage  of  re- 
serve, 64;  use  of  reserve  64. 

Food  preparation  the  function 
of  leaves,  82. 

Food  supply,  relation  of  rcots 
to,  78;  unfavorable,  effect  of, 
on  plant,  151. 

Formaldehyd,    181. 

Formalin  treatment  for  grain 
smut,  181. 

Formative    pruning,    256. 

Formula  for  Bordeaux  mix- 
ture, 183. 

Formulas  for  kerosene  emul- 
sion, 168;  for  resin  washes;,  168. 


Freezing  of  plants  favored  by 
much  water  in  plant  tissue  122. 

Freezing,  severe,  may  split 
open  tree  trunks  125. 

Frost,  conditions  that  tend  to 
avert,  134;  how  foretold.  131; 
plants  injured  by,  how  saved 
from  serious  damage,  124; 
liability  to,  depending  com- 
paratively little  upon  lati- 
tude, 135;  localities  most  sub- 
ject to,  135;  methods  of  pre- 
vent.ng  injury  by,  136. 

Frozen  tissues,  treatment  of, 
124. 

Fruit,  104;  or  flowers,  pruning 
for,  263;  thinning  of,  105,  263. 

Fru.itfulness  promoted  by  re- 
stricting growth  current  63. 

Fruiting,  obstructing  growth 
current  to  promote,  265;  root 
pruning  to  promote,  264. 

Fruits  and  vegetables,  cracks 
in,  caused  by  excessive  moist- 
ure, 140;  rarely  develop  with- 
out fecundation,  104;  ripen- 
ing cf,  106. 

Fungi,  179;  endophytic,  181; 
epiphytic,  181;  methods  of 
controlling,  180. 

Fungicides,  180;  various,  182,  185. 

Funguous  diseases.  need  of 
consulting  specialists  in,  185. 

Gathering  and  storing  of  seeds, 
106. 

Genera,   how    formed,    18. 

Generic  name   defined,   20. 

Genus,   how   formed,    18. 

Germinating  power,  duration 
of,  108. 

Germination  defined,  24;  de- 
pendent on  stage  of  matur- 
ity of  seeds,  106;  hastened  by 
compacting  soil,  28;  hastened 
by  mutilating  seed-case,  30; 
hastened  by  soaking  seeds, 
29;  in  water,  27;  moisture  es- 
sential to,  25;  not  hindered 
by  light.  32;  oxygen  essential 


Index. 


295 


Germination— 

to,  26;  promptness  in,  im- 
portant, 28;  requisites  for. 
28;  retarded  by  excess  of 
water,  29;  seed-case  in,  33; 
temperature  at  which,  takes 
place,  26;  time  required  for, 
32;  warmth  essential  to,  25; 
when  completed,  25. 

Germinations,  earlier,  form 
more  vigorous  plantlets,  .38. 

Girdling,    killing    trees    by.    63. 

Glumes,     99. 

Gooseberry    mildew,    184. 

Gophers,   damage   from,   161. 

Gormands   on   fruit  trees,    140. 

Graft,    219. 

Grafting,  approach,  234,  221; 
cion,  221;  cleft,  226,  224;  cord, 
224;  herbaceous,  228,  234;  how 
possible  54;  objects  of.  220; 
paper,  224;  plants  uniting 
by,  220;  propagation  by,  219;- 
root,  221;  side,  228;  top,  226; 
veneer,  229;  wax,  how  made, 
222;  Whip,  224. 

Grafts,    whole    root,    226. 

Gramineae,    flowers    of,    99. 

Grape    mildew,    182. 

Grass    family     flowers    of,    99. 

Grasshoppers,    171. 

Greenhouse,  205;  heating  de- 
vices for,  206. 

Growing    point    defined,    51. 

Growth     by     cell     division, 


to 


15, 
pro- 


decline 
in  di- 
54; of 


cutting  back  new. 
mote  flowering,  264; 
of,  111;  defined,  15 
ameter,  of  stems, 
roots  in  length,  71;  pruning 
for,  263;  retarded  by  insuffi- 
cient moisture  in  soil.  142; 
tardy  starting  of,  after  trans- 
planting. 251;  water  neces- 
sary to,  45. 

Growth  current,  obstructing,  to 
promote  flowering  and  fruit- 
ing, 265;  restriction  of,  pro- 
motes fruitfulness,  63. 

Guard    cells,    50,    51. 


Hardiness  defined,  13;  depend- 
ent on  degree  of  dormancy, 
114. 

Healing    of    wounds,    56. 

Health    defined,    13. 

Heat,  excessive,  how  affecting 
plants  118. 

Hedge   shears,    267. 

Heeling-in    plants,    241. 

Hellebore    powder,    166,    167. 

Hemp,    broom    rape   of,    179. 

Herbaceous   grafting,    228,    234. 

Herbaceous   stems   defined,    53. 

Heredity  and  variation,    16. 

Hermaphrodite    flowers,    102. 

Hoarfrost,    cause    of,    130. 

Horizontal    extent    of    roots,    76. 

Host   (of  parasites)   defined,    21. 

Hotbed,    the,    204. 

Hotbeds  require  care  in  ven- 
tilation, 70. 

Hot  water,  for  destroying  in- 
sects, 170. 

Humidity,  methods  of  con- 
trolling, 208. 

Hybrids    and  crosses    defined,  20. 

Hydrocyanic    gas,    169. 

Hydrogen,  source  of,  in  plants, 
44. 

Hyphae,    180. 

Hypocotyl,  defined,  32;  devel- 
ops differently  in  different 
species,  36;  roots  start  from, 
35;  seeds  in  which  it  length- 
ens must  be  planted  shal- 
low. 36. 

Ice    often    destroys    low    plants, 

127. 

Immature  vs.    ripe   seeds,   107. 
Imperfect  flowers,   103. 
Implements,     for    pruning,     267; 

for     transplanting,      245,      246, 

247. 
Improvement     possible     through 

plant  variability,  271. 
Individuals  defined,  18. 
Injury  by  cold,  methods  of 

averting,    127. 


296 


Index. 


Insecticides,  163;  apparatus  for 
applying,  171;  use  of.  173. 

Insects  beneficial,  162;  bur- 
rowing, 174;  destroying  by 
poisons  or  caustics,  163;  eat- 
ing-insects, 173;  hand-pick- 
ing, 163;  injurious,  life  his- 
tory of,  1,8;  leaf -eating,  174; 
ravages,  method  of  prevent- 
ing, 162;  repelling,  by  means 
of  Oi^ensive  odors,  163;  root- 
eating,  174,  175;  sucking,  173, 
177. 

Insects     trapping,    162. 

Internodes,  defined,  80;  stem 
lengthens  by  elongation  of, 
81;  ultimate  length  of,  81. 

Iron  essential  to  formation  of 
chlorophyll,  45. 

Irrigation,    144. 

Kainit,    157. 

Kerosene,  applied  with  water. 
168;  as  an  insecticide,  168; 
emulsion,  168. 

Killing   trees    by  girdling,    63. 

Knife.'  budding,  233;  grafting, 
223;  pruning  267. 

Knowledge,  application  of,  es- 
sential to  success,  9. 

Lath  screen  for  shading  plants, 
145. 

Leaf-buds,  88;  comparative 
vigor  of.  91. 

Leaf  cuttings,  propagation  by. 
218. 

Leaf  development,  importance 
of,  83. 

Leaf  fall,  time  of,  an  index  of 
wood  maturity,  113. 

Leaf-eating    irsects,    174. 

Leaf   miners.    175     176. 

Leaves,  82;  are  usually  short- 
lived, 85;  comparative  size  of, 
84;  function  cf,  82;  manurial 
value  of,  85. 

Leguminous  plants  enrich  the 
soil  with  nitrogen,  79,  156. 

Lenticels,    51. 


Lever  shears,    268. 

Life,    culture    deals    with,    12. 

Life,    what    is    it?    12. 

Lifting   large    trees,    238. 

Lifting  the  plant,  directions 
for.  239. 

Light  does  not  hinder  germina- 
tion, 32. 

Light,  unfavorable,  how  affect- 
ing the  plant,  145. 

Living  beings,  cellular  struc- 
ture of,  13. 

Localities  most  subject  to  un- 
timely frosts,  135. 

Locusts,    171. 

London    purple,    165. 

Low  plants  often  destroyed  by 
ice,  127. 

Magnesium,  part  played  by,  in 
plant,  45. 

Mallet   cuttings,    212. 

Manure  increases  water-hold- 
ing capacity  of  soil,  45. 

Manurial   value   of   leaves     85. 

Maturative    pruning.    266. 

Maturity  of  plants,  influence  of 
drought  on,  142. 

Maximum    defined,    25. 

Mealy   bug,    170. 

Melons,  screen-covered  frame 
for  protecting  hills  of.  162. 

Mice,    damage   from,    160. 

Minimum    defined,    25. 

Moisture,  an  enemy  to  stored 
seeds,  109;  essential  to  ger- 
mination, 25;  excessive,  caus- 
ing cracks  in  fruits  and 
vegetables,  140;  excites  root 
growth  66;  excessive,  in  air, 
injurious  to  plants,  141;  in- 
sufficient, in  air  causing  ex- 
cessive transpiration,  142;  in- 
su.-cient,  in  soil  retards 
growth,  142. 

Mohocotyledones    defined,    36. 

Monoecious    flowers,    102. 

Mound-layering,    195. 


Index. 


297 


Mulching,  tends  to  prevent 
drought,  144;  transplanted 
stock,  250. 

Muriate    of    potash,    157. 

Names,    scientific,   why  used,  19. 

Nitrates  in  the  soil,  sources 
of,  154. 

Nitrification,    154,    155. 

Nitrogen,  154,  155;  in  proto- 
plasm, 45;  in  rain  and  snow, 
155;  sources  of,  in  plant,  45; 
stimulates  growth,  152. 

Nodes    defined,    80. 

Northerly  exposure  least  try- 
ing to  plants  in  winter,  129. 

Notching,    253,    265. 

Nursery  trees  benefited  by 
transplanting,  76. 

Oats,  treatment  of  seed  for 
prevention  of  smut,  181. 

Objects  of  grafting,  220;  of 
pruning,  256. 

Oedema  in  plants,  caused  by 
excessive  watering,  139. 

Onion    mildew,    182. 

Optimum     defined,     25. 

Orange    rust,    180. 

Organic  manures,  partially  de- 
composed, act  more  promptly 
than  fresh  ones,  155. 

Organic  matter,  importance  of, 
in  soil,  69. 

Osmosis   defined,    61. 

Ovary,    97. 

Overbearing  should  be  pre- 
vented, 105. 

Ovule,    97. 

Oxygen,  essential  to  germina- 
tion 26;  necessary  to  life  of 
roots,  66;  source  of,  in 
plants,  44. 

Oyster-shell    bark-louse,    168. 

Packing    plants    for    transporta- 
tion,   239. 
Pales,    100. 
Palets,   100. 
Palisade    cells,    49. 


Parasites,  animal,  160;  defined. 
21;  flowering  or  phaneroga- 
mic, 178;  funguous,  179;  In- 
jurious, 159;  vegetable,  178. 

Parenchyma,    51. 

Paris  green,    164. 

Pear,    blight   of,    180,    266. 

Peeling  the  stems  of  trees, 
57,  265. 

Perfect    flowers,    102. 

Persian    insect    powder,    166. 

Petals,    96. 

Phosphorus,  157;  part  played 
by,  in  plants,  45. 

Picturesqueness,  pruning  for, 
258. 

Pinching  defined,  252;  stimu- 
lates branching,  82;  to  pro- 
mote flowering.  263. 

Pistil.    97. 

Pith,    52. 

Plant  food,  elements  in,  44;  ele- 
ments of,  likely  to  be  defi- 
cient, 45;  from  soil  must  be 
dissolved  by  soil  water,  44; 
in  soil,  reduced  by  crop 
growing,  153;  sources  of,  43. 

Plant  improvement,  how  ex- 
plained, 270. 

Planting,  too  close,  causes  de- 
ficient light,  148;  trees,  direc- 
tions for,  242  245;  with  ref- 
erence to  chance  crossings, 
279;  with  reference  to  polli- 
nation, 103. 

Plantlet,  inner  structure  of,  48; 
may  need  help  to  burst  seed- 
case,  34 ;  principal  parts  of, 
41;  vigor  of,  proportionate  to 
size  of  seed,  38;  visible  in 
seed,  40. 

Plant    life,    round    of,    22,    116. 

Plant  manipulation,  189;  pro- 
pagation, 189. 

Plant,  directions  for  lifting 
the.  237;  removing  the,  239. 

Plant  tissues,  brittleness  of, 
60;  killed  by  drying,  144; 
toughness  of,  caused  by 
drought,  143. 


298 


Index. 


Plants,  abnormal  development 
of  due  to  Insufficient  light, 
147;  affected  by  unfavorable 
environment,  118;  difference 
in  water  requirements  of,  139; 
distance  apart  for  growing, 
83;  domestic,  defined,  11; 
have  improved  under  culture, 
270;  heeling-in,  241;  Injured 
by  excessive  water,  139;  af- 
fected by  parasites,  159;  only 
can  prepare  food  from  min- 
eral substances.  43;  packing 
for  transportation,  239;  pot- 
ted, require  drainage,  70; 
potting  and  shifting,  247; 
power  of,  to  endure  cold,  122; 
preparation  of,  for  replant- 
ing, 242;  rapid-growing,  re- 
quire much  water,  138;  shad- 
ing after  transplanting,  146; 
those  who  improve,  are  true 
benefactors,  279. 

Plants  under  glass  liable  to 
suffer  from  deficient  light, 
148;  need  of  rest  of,  113; 
not  to  be  sprinkled  in  bright 
sunshine,  119;  plants,  unpack- 
ing, 241;  variability  of,  271; 
washing  the  roots  of  pud- 
dled, 242;  watering  of  potted, 
70,  138;  watering  the  roots  of 
recently  transplanted,  250; 
screens  for  shading,  145,  146. 

Plum,    black    knot    of,    180,    266. 

Plum    curculio,    176,    177. 

Plumule,   41. 

Poisons,  destroying  insects  by. 
163. 

Pollen,  97;  appearance  of  ma- 
ture, 276;  applying,  277;  to 
prevent  access  of  undesired, 
276. 

Pole   shears,    268. 

Pollination,  101;  in  many  plants 
dependent  on  wind,  151; 
planting  with  reference  to, 
103;  to  prevent  self,  276; 
when  should  it  be  performed, 
277. 


Potash,    caustic,    168. 

Potassium,  157;  assists  in  food 
preparation,  45;  -sulfid  solu- 
tion, 184. 

Potato,  beetle,  163,  165;  blight 
of,  184;  foliage  of,  injured  by 
sun  heat,  121. 

Potato    plant,     illustrated,    79. 

Potatoes,    knobby,   141. 

Potted  plants  require  drainage, 
70;  watering  of,  70,  138,  139. 

Potting,  and  shifting,  247;  soil 
248. 

Powdery  mildews,   185. 

Preparation  of  plants  for  re- 
planting, 242. 

Prepared   food,   current   of,   62. 

Pricking   off  seedlings,    76. 

Principle     of    selection,     17,  270. 

Propagating  bed,    the,    207. 

Propagation  by  cuttings,  200; 
by  detached  parts,  196;  by 
division,  181,  190;  by  di- 
vision of  the  crown,  196; 
by  grafting,  219;  by  layers, 
195;  by  parts  intact.  192;  by 
sections  of  the  plant,  199;  by 
seeds,  190;  by  specialized 
buds,  196;  by  stolons,  194;  by 
suckers,  193;  methods  of,  190. 

Prosenchyma,    51. 

Protective   pruning,    266. 

Protoplasm,  active  state  of,  15; 
dormant  state  of,  15;  some 
properties  of,  15. 

Proximal   defined,    80. 

Pruning,  defined,  252;  for  den- 
sity, 259;  for  flowers  or  fruit. 
263;  for  growth,  263;  for  pic - 
turesqueness,  258;  for  slen- 
derness,  258;  for  stockiness, 
258;  for  strength,  260;  for 
symmetry,  256;  formative, 
256;  implements,  267;  insuf- 
ficient, prevents  formation  of 
fruit  buds,  149;  -knife,  267; 
maturative,  266;  objects  of, 
256;  protective,  266;  -saw, 
267;  season  for.  254;  -shears, 
267;  stimulative,  262;  where 


Index. 


Pruning — 

and   how   to   make    the   cut  in, 
254. 

Psychrometer,    sling,    131. 

Puddled  plants,  washing  roots 
of,  242. 

Puddled  soil  defined,  26;  pre- 
vents germination,  27. 

Puddling  the  roots  of  trees,  240. 

Pumpkin,  provision  in  to  ai'd 
plantlet  to  emerge  from  seed- 
case,  34,  35. 

Pyrethrum   powder,    166. 

Rabu.cs,    damage    from,    161. 

Radicle,    33. 

Raspberry    pruning   hook.    268. 

Rate  of  root  growth,   78. 

Reduced  vigor,  tendencies  of,  13. 

Reducing  the  tops  of  trees  prior 
to  planting,  242. 

Removing   the   plant,    239. 

Reproduction  defined,  16;  rela- 
tion to  growth,  16;  sexual 
and  non-sexual,  16. 

Reserve  food,  15;  how  plants 
use,  64;  how  to  promote  ac- 
cumulation of,  91;  storage  of, 
64. 

Resin  washes,   168. 

Rest  period,  111;  not  peculiar 
to  temperate  '  zones,  112; 
plant  processes  may  not  en- 
tirely cease  during,  116. 

Reversion.     271. 

Richards'  transplanting  tools, 
246. 

Ring-budding.    231,    234. 

Ringing,  defined,  253;  often 
causes  formation  of  flower- 
buds,  94. 

Ripening  of  fruits,    106. 

Root,  and  the  soil,  65;  office  of, 
65;  originates  in  stem,  65; 
starvation,  63. 

Root  branching,  conditions  af- 
fecting, 74. 

Root  branching,  how  stimu- 
lated, 75;  should  be  encour- 
aged. 74. 


Root  cap,    71, 

Root   cuttings,    213,    214. 

Root  grafting,    225. 

Root  grafts,  tools  for  planting, 
246. 

Root  growth,  excited  by  moist- 
ure, 66;  rate  of,  78. 

Root-hairs  absorb  water  with 
considerable  force,  73;  apply 
themselves  to  soil  particles, 
72;  70;  dissolves  soil  parti- 
cles, 72;  nature  of,  49,  71; 
show  need  of  roots  for  air, 
67. 

Root  killing   of  trees,    126. 

Root  pruning  to  promote  flow- 
ering and  fruiting  264;  stim- 
ulates root  branching,  75.  76. 

Root    tubercles,    79. 

Roots,  depth  of,  in  soil,  77;  de- 
stroyed by  excessive  water 
in  soil,  137;  growth  of  in 
length,  71;  horizontal  extent 
of,  76;  of  trees,  puddling, 
i40;  only  youngest  active  in 
aosorption,  74;  oxygen  neces- 
sary to  life  of,  66;  properly 
and  improperly  planted,  243; 
relation  of,  to  food  supply, 
78;  replanting  the,  242;  start 
from  hypocotyl,  35;  trimming 
of,  prior  to  planting,  242; 
washing,  of  puddled  plants, 
242;  wetting,  prior  to  plant- 
ing, 243. 

Root-tip,  how  penetrates  the 
soil,  70. 

Root-tips,  formation  of  should 
be  encouraged,  74. 

Rotation    of   crops,    158. 

Rose   beetle,    163. 

Rosin   washes,    168. 

Round  of  plant  life,  the  22. 
116. 

Rust    of    blackberry,    180. 

Sacking  the  roots   of  trees,   239. 

Saltpeter,    157. 

Sap  defined,   46. 

Sap,    flow    of    in    spring,    61. 


300 


Index. 


Sap -sprouts    on   fruit  trees,   140. 

Saw,    pruning,    268. 

Science  and  art  denned,  9;  how 
best  learned,  10. 

Scientific   names,    why   used,    20. 

Scion,    220. 

Screens  for  shading  plants, 
145.  146. 

Season   for   pruning,    254. 

Seed,  104;  age  of,  as  affecting 
the  resulting  crop,  110;  ma- 
turing of,  injures  fodder 
crops,  105;  plantlet  visible  in, 
40;  production  of  exhausts 
plants,  104;  selection,  im- 
portance of,  273;  vigor  of 
plantlet  proportionate  to  size 
of,  38;  vitality,  conditions  af- 
fecting duration  of,  108. 

Seed-case  defined,  23;  influence 
of  on  absorption  of  water  by 
seeds,  23;  in  germination,  33; 
is  useless  after  germination 
commences,  33;  plantlet  may 
need  help  to  burst,  34. 

Seeding,  prevention  of,  pro- 
longs the  life  of  plants,  105. 

Seed-leaves   defined,   36. 

Seedlings,  pricking  off  young, 
76;  selection  of  crossed.  278; 
variation  produced  by  grow- 
ing. 274;  young,  injured  by 
unobstructed  rays  of  sun,  145. 

Seeds  absorb  water  by  contact, 
22;  a  few  germinate  in  water, 
27;  drying  of,  how  affecting 
their  vitality,  110;  earlier 
germinating,  form  more  vig- 
orous plantlets,  38;  gathering 
and  storing  of,  106;  germina- 
tion hastened  by  mutilating 
seed-case,  30;  how  deep 
should  they  be  planted?  38, 
191;  immature  vs.  ripe.  107; 
in  which  hypocotyl  lengthens 
must  be  planted  shallow,  36; 
of  pumpkin  family  should  be 
planted  flatwise,  34;  rate  at 
which  they  absorb  water,  22; 
should  be  tested  before  plant- 


Seeds — 

ing.  31;  should  not  be  planted 
until  soil  becomes  warm,  29; 
stored,  moisture  an  enemy 
to,  109;  stratification  of,  111; 
very  small,  should  not  be 
covered,  39,  191;  vitality  of, 
limited  by  age,  108;  why 
cover,  at  planting,  33;  why 
they  fail  to  germinate,  30; 
testing,  directions  for,  31; 
-tester  described.  31. 

Selection  a  means  of  fixing 
variations,  272;  of  crossed 
seedlings,  278;  of  seed,  im- 
portance of,  273;  of  subjects 
for  crossing,  275;  principles 
of,  17,  270. 

Self    pollination,    102. 

Sepal,    96. 

Sexual    reproduction,    16. 

Shading  plants  after  trans- 
planting. 251. 

Shears,  hedge,  269;  lever,  269; 
pole,  268;  pruning,  268. 

Shed  screen  for  shading  plants, 
145. 

Shield  budding,    231. 

Shifting    plants,     248. 

Side    grafting,    228. 

Sifting  box  for  applying  in- 
secticide powders,  171. 

Slenderness,    pruning   for,    258. 

Slips,   214. 

Slugs,    162. 

Smut  of  the  small  grains,  181; 
of  corn,  180;  of  onion.  181. 

Snails,     162. 

Sodium    nitrate.    156. 

Soil,  and  the  root.  65;  a  scene 
of  constant  changes,  68;  com- 
pacting, about  seeds  hastens 
germination.  28;  compacting 
wet,  may  prevent  germina- 
tion, 27;  depth  of  roots  in, 
77;  how  penetrated  by  root- 
tip,  70;  ideal,  for  land  plants, 
68;  importance  of  organic 
matter  in,  69;  needs  ventila- 
tion, 69;  particles  of.  dis- 


Index. 


301 


Soil- 
solved    by    root-hairs,    72;    for 
potting,  248;   puddled,  defined, 
26;    puddled,    prevents    germi- 
nation,   27. 

Soil  aeration  promoted  by 
drainage,  70;  promotes  soil 
fertility,  155. 

Species,   18. 

Specific   names   defined,    20. 

Spikelet,    99. 

Splice   grafting,    224. 

Splitting  down,  to  prevent 
branches  from,  262. 

Spore  germination  favored  by 
moisture,  185;  prevention  of. 
181. 

Spores  defined,  39;  non -sexual, 
16;  of  ferns,  how  planted,  39. 

Spraying    outfit,     steam,    173. 

Spray   pump,    172. 

Sprinkling  of  plants  under 
glass  to  be  avoided  in  bright 
sunshine,  119. 

Squash,  provision  in,  to  aid 
plantlet  to  emerge  from  seed- 
case,  34;  bug,  173;  -vine 
borer,  163. 

Stable   manure,    158. 

Staking  trees  to  prevent  shak- 
ing by  the  wind.  245. 

Stamens,    97. 

Starvation   of  roots,    63. 

Stem  and  root  development  de- 
pendent on  number  of  leaves, 
83. 

Stem    defined,    79. 

Stem,  fastest  elongation  of,  82; 
how  lengthens,  81;  root  origi- 
nates in,  65;  vital  part  of 
woody,  55. 

Stem  cuttings,  211;  how  plant- 
ed, 212;  proper  length  of,  212. 

Stems,  how  they  increase  in 
diameter,  54;  underground,  80. 

Stigma,    97. 

Stimulative     pruning,    262. 

Stocks   for   grafting,    225. 

Stockiness,     pruning    for,    258. 

Stoma    defined,    50. 


Stomata  defined,   50. 

Storage  of  cuttings,  210;  of  re- 
serve food,  64. 

Stratification    of    seeds,    111. 

Strawberry,  perfect  and  im- 
perfect flowers  of,  103. 

Strength,    pruning   for,    260. 

Striped   cucumber  beetle,    162. 

Subjects  for  crossing,  selection 
of,  275. 

Style.    97. 

Suckering    defined,    253. 

Sulfate   of  potash,    157. 

Sulfur,  part  played  by  in 
plants,  45. 

Sun  heat  injurious  to  young 
seedlings,  145. 

Sun-scald,    120. 

Superphosphate,    157. 

Symbiosis,    154. 

Table  for  computing  dew  point, 
133;  showing  duration  of  seed 
vitality,  108;  showing  germi- 
nating temperatures  of  seeds, 
26. 

Tarred-paper  cards,  tool  for 
cutting,  175. 

T-Budding,    2al. 

Temperature  as  affecting  plant 
growth,  118;  fatal  to  proto- 
plasm, 119;  influence  of  on 
absorption  of  water  by  seeds 
23;  methods  of  controlling,  202. 

Tenderness  defined,   13. 

Terminal  buds,  pinching  of,  ef- 
fect on  wood  maturity,  128; 
destructi'on  of,  by  cold,  124. 

Theory    of    evolution,    21. 

Thermal    belts,    135. 

Thinning   fruit,   105,    263. 

Time,  most  favorable  for  trans- 
planting, 236. 

Tobacco,  broom  rape  of,  178; 
decoction  of,  for  destroying 
aphide.  167;  smoke  for  de- 
stroying insects,  167;  fluid 
extract  of,  167;  topping,-  253, 
263;  -worm,  163;  frenching, 
139. 


302 


Index. 


Tomato   worm,    163. 

Tongue   grafting,    224. 

Tool  for  injecting  poisonous 
liquids,  174;  for  cutting  paper 
cards,  174. 

Top    grafting,    225. 

Topping,  defined,  253;  tobacco, 
263. 

Transpiration,  amount  of,  59; 
conditions  affecting,  58;  cur- 
rent, 60;  defined,  58;  exces- 
"sive,  59;  excessive,  caused  by 
insufficient  moisture  in  the 
air,  142;  increases  with  de- 
gree of  heat,  118. 

Transplanted  plants,  shading, 
251;  watering,  250. 

Transplanted  stock,  tardy 
starting  of,  251. 

Transplanter,  Baldridge,  247; 
Bemis,  247. 

Transplanting,  235;  benefits 
nursery  trees  76;  endured 
best  by  vigorous  plants,  236; 
most  favorable  time  for,  236; 
stimulates  root  branching, 
75;  devices  for,  245. 

Transplanting  tools,  Richards'. 
246. 

Trapping    insects,    162. 

Tree  trunks  split  open  by  se- 
vere freezing,  125. 

Trees,  bundling  for  transporta- 
tion, 239;  detrimental  to 
neighboring  crops,  59;  direc- 
tions for  planting  243;  kill- 
ing by  girdling,  63;  lifted  or 
lowered  to  accommodate 
grading,  238;  lifting  large, 
237;  nursery,  benefited  by 
transplanting.  76;  puddling 
roots  of,  240;  reducing  top  of, 
prior  to  planting,  242;  sack- 
ing roots  of,  241;  staking,  to 
prevent  shaking  by  wind,  245. 

Trimming  defined,  253;  roots 
prior  to  planting,  242. 

Tuber,    the,    198. 

Tubercles    on    roots.    78. 

Turn   of   the   year,    115. 


Underground  stems,    80. 
Unhealed    wounds    introduce  de- 
cay,   255. 

Unisexual  flowers,   102. 
Unpacking   plants,    241. 

Variability  of  offspring  of 
crosses  and  hybrids,  20;  of 
plants,  271. 

Variation,  and  heredity,  16; 
how  can  we  produce,  273; 
may  take  place  in  any  direc- 
tion, 17;  produced  by  cross- 
ing, 274;  produced  by  cul- 
ture, 273;  produced  by  grow- 
ing seedlings,  274. 

Variations,  how  to  fix  desir- 
able, 271;  not  always  perma- 
nent, 271. 

Varieties,  18;  origin  of  culti- 
vated, 270. 

Vascular  bundles  defined,   51. 

Vegetables,  cracks  in  caused 
by  excessive  moisture,  140. 

Ventilation,  hotbeds  require 
care  in,  70;  soil  needs,  69. 

Veneer  grafting,   229. 

Vigor  defined,  12;  of  plantlet 
proportionate  to  size  of  seed, 
38;  tendencies  of  reduced, 13. 

Vital  part  of   woody  stems,   55. 

Warmth  essential  to  germina- 
tion, 25. 

Washing  the  roots  of  puddled 
plants.  242. 

Water,  adequate  supply  of  most 
importance,  45;  excess  of,  re- 
tards germination,  29;  ex- 
cessive in  soil  destroys  roots, 
137;  force  causing  to  rise  in 
stems,  62;  insufficient,  how 
affecting  plants,  142;  manur- 
ing increases  capacity  of  soil 
for,  45;  of  plants  almost 
wholly  absorbed  by  root- 
hairs,  46;  only  youngest  roots 
absorb,  74;  plants  contain 
large  amounts  of,  57;  root- 
hairs  absorb,  with  force,  73; 
seeds  absorb,  by  contact,  22. 


Index. 


303 


Water-sprouts  on  fruit  trees. 
140. 

Water  supply,  unfavorable,  the 
plant  as  affected  by,  137. 

Watering,  excessive,  may  pro- 
duce a  dropsical  condition, 
139;  copious,  at  intervals 
preferable  to  frequent  slight 
watering,  138;  injudicious, 
138;  of  potted  plants,  70;  re- 
cently -  transplanted  plants, 
250. 

Weeds,  186;  annual,  biennial 
and  perennial,  186;  cause  de- 
ficient light  in  low-growing 
crops,  148;  how  destroyed, 
63;  plants  as  affected  by,  186. 

Wet-bulb    depression.    133. 

Whip -grafting,    224. 

White    grubs,     163. 

White  hellebore,  166. 


Whole-root  grafts,   226. 

Wind   breaks,   129. 

Wind,  excessive,  effect  of,  on 
plants,  150;  insufficient,  effect 
on  the  plant,  150;  insufficient, 
promotes  damage  from  frost, 
151;  insufficient,  promotes  de- 
velopment of  fungous  para- 
sites, 150;  tends  to  avert 
frost.  134;  unfavorable,  how 
affecting  the  plant,  150. 

Wood  ashes,   158. 

Woodchucks,    damage   from,  161. 

Wood,    darkening    of,    124. 

Wood,  maturity  of,  favored  by 
a  dry  soil,  127;  by  pinching 
terminal  buds,  128;  indicated 
by  leaf  fall,  113. 

Wounds,  healing  of,  56;  un- 
healed,  introduce  decay,  255. 


9414 


UNIVERSITY  OF  CALIFORNIA  AT  LOS  ANGELES 

THE  UNIVERSITY  LIBRARY 
This  book  is  DUE  on  the  last  date  stamped  below 

APR  2  6  I95u 
K^  il  1959 


SB92 
G55p 
1906 


WCH, 

1FORN1A, 


UF. 


